Diving Certifications by Agency

Recreational, technical, rebreather, cave, and professional certifications by agency, with prerequisites and limits.

Prerequisites and limits summarize each agency's published standards and change over time. Your agency's current standards and your instructor decide what a certification allows.

PADI Professional Association of Diving Instructors

PADI certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Scuba Diver (SD)Recreational	Minimum age 10 years Medical clearance as required Basic swimming ability	Training-level certification Must dive under direct supervision of a professional Maximum depth 12 m (40 ft) No decompression dives No overhead environment
Open Water Diver (OWD)Recreational	Minimum age 10 years (or 15 for full certification) Basic swimming ability Medical clearance as required	Recommended max depth 18 m (60 ft) No decompression dives No overhead environment
Advanced Open Water Diver (AOWD)Recreational	PADI Open Water Diver Minimum age 12 years	Recommended max depth 30 m (100 ft) for adults, 21 m (70 ft) for 12-14 years No decompression dives No overhead environment
Rescue Diver (RD)Rescue	PADI Advanced Open Water Diver Minimum age 12 years Current CPR/First Aid certification (e.g., EFR Primary and Secondary Care)	Not a depth rating Focus on problem prevention and management
Master Scuba Diver (MSD)Recreational	PADI Rescue Diver Five PADI Specialty Diver certifications Minimum 50 logged dives	Recognition rating; no new depth privileges by itself
Enriched Air (Nitrox) Diver (EAN)Specialty	PADI Open Water Diver Minimum age 12 years	Use of nitrox mixes within agency limits (commonly up to 40% O2) Plan PPO2 ≤ agency recommended values No decompression dives unless otherwise qualified
Deep DiverSpecialty	PADI Advanced Open Water Diver Minimum age 15 years	Training to dive to 40 m (130 ft) within recreational limits No staged decompression
Tec 40Technical	PADI Advanced Open Water Diver PADI Enriched Air (Nitrox) Diver PADI Deep Diver Minimum age 18 years Minimum 30 logged dives Recent diving activity	Intro technical level Limited decompression within training standards One decompression gas (common: up to 50% O2)
Tec 45Technical	PADI Tec 40	Extended decompression Use of a single high-O2 decompression gas (often up to 100% O2) Complex dive planning and emergency procedures
Tec 50Technical	PADI Tec 45	Use of two decompression gases Deeper/longer staged decompression dives per standards
Tec Trimix 65Technical	PADI Tec 50	Trimix for dives up to ~65 m (210 ft) Helium-based mixes Multiple deco gases
Tec Trimix DiverTechnical	PADI Tec Trimix 65	Full trimix training for very deep dives (commonly cited up to ~90 m/300 ft) Multiple decompression gases Complex staged decompression
Tec 40 CCR DiverRebreather	PADI Advanced Open Water Diver PADI Enriched Air (Nitrox) Diver Minimum age 18 years Unit-specific prerequisites Manufacturer unit-specific training requirements	CCR air or nitrox diluent within training depth Unit-specific configuration and bailout procedures
Tec 60 CCR DiverRebreather	PADI Tec 40 CCR Diver	Deeper CCR dives with staged decompression Helitrox/mixed gas per standards
Tec 100 CCR DiverRebreather	PADI Tec 60 CCR Diver	Advanced mixed-gas CCR dives with significant decompression obligations Unit-specific bailout and planning standards
Divemaster (DM)Professional	PADI Rescue Diver Minimum age 18 years Minimum 40 logged dives to start, 60 to certify Current EFR Primary and Secondary Care or equivalent Medical clearance within 12 months	May supervise certified divers May assist with training May not conduct courses independently
Assistant Instructor (AI)Professional	PADI Divemaster Minimum age 18 years Minimum 60 logged dives Certified diver for at least six months Emergency First Response Primary and Secondary Care within the past 24 months Medical clearance within 12 months	May teach knowledge development and confined water skills under an instructor's supervision May not certify divers independently
Open Water Scuba Instructor (OWSI)Professional	PADI Divemaster Minimum age 18 years Minimum 60 logged dives to start the IDC, 100 to attend the Instructor Examination Certified diver for at least six months PADI Assistant Instructor rating or the complete Instructor Development Course (IDC) Emergency First Response Instructor rating (may be earned during training) Emergency First Response Primary and Secondary Care within the past 24 months Medical clearance within 12 months Pass the PADI Instructor Examination (IE)	May independently teach and certify divers through PADI Divemaster Specialty courses require the matching Specialty Instructor rating
Specialty Instructor (SI)Professional	PADI Open Water Scuba Instructor PADI Instructor rating in good standing Specialty Instructor Training Course, or application with the diving experience the specialty requires	May teach the specific PADI specialty course each rating covers One rating per specialty
Master Scuba Diver Trainer (MSDT)Professional	PADI Open Water Scuba Instructor PADI Specialty Instructor PADI Instructor rating in good standing At least 25 PADI divers certified At least five PADI Specialty Instructor ratings	May teach every course needed to take a diver to Master Scuba Diver Prerequisite for IDC Staff Instructor and for many TecRec instructor ratings
IDC Staff Instructor (IDCS)Professional	PADI Master Scuba Diver Trainer PADI Master Scuba Diver Trainer rating IDC Staff Instructor course	May assist a Course Director with instructor training May not run an IDC independently
Master Instructor (MI)Professional	PADI IDC Staff Instructor PADI IDC Staff Instructor rating Teaching experience, certifications issued and courses taught per PADI standards Application and PADI approval	Recognition rating; teaching scope is that of the underlying instructor ratings
Course Director (CD)Professional	PADI Master Instructor PADI Master Instructor rating, or IDC Staff Instructor meeting the published criteria Selection for and completion of the Course Director Training Course (CDTC)	May conduct Instructor Development Courses and certify PADI instructors
Wreck DiverSpecialty	PADI Advanced Open Water Diver Minimum age 15 years	External wreck exploration Limited penetration within daylight zone
Underwater Navigator (Nav)Specialty	PADI Open Water Diver Minimum age 10 years	None listed
Night DiverSpecialty	PADI Open Water Diver Minimum age 12 years	None listed
Drift Diver (Drift)Specialty	PADI Open Water Diver Minimum age 12 years	None listed
Peak Performance Buoyancy (PPB)Specialty	PADI Open Water Diver Minimum age 10 years	None listed
Search and Recovery Diver (S&R)Specialty	PADI Advanced Open Water Diver Minimum age 12 years	None listed
Underwater PhotographerSpecialty	PADI Open Water Diver Minimum age 10 years	None listed
Sidemount DiverSpecialty	PADI Open Water Diver Minimum age 15 years	None listed
Dry Suit DiverSpecialty	PADI Open Water Diver Minimum age 10 years	None listed
Ice DiverSpecialty	PADI Advanced Open Water Diver PADI Dry Suit Diver Minimum age 18 years	None listed
Altitude Diver (Altitude)Specialty	PADI Open Water Diver Minimum age 10 years	None listed
Boat Diver (Boat)Specialty	PADI Open Water Diver Minimum age 10 years	None listed
Equipment Specialist (Equipment)Specialty	PADI Open Water Diver Minimum age 10 years	None listed
Self-Reliant Diver (Solo)Specialty	PADI Advanced Open Water Diver Minimum age 18 years Minimum 100 logged dives	None listed
Underwater Videographer (UW Video)Specialty	PADI Open Water Diver Minimum age 10 years	None listed
Emergency Oxygen ProviderOther	None listed	None listed

SSI Scuba Schools International

SSI certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Scuba Diver (SD)Recreational	Minimum age 10 years Basic swimming ability Medical clearance as required	Training-level certification Must dive under direct supervision of a professional Maximum depth 12 m (40 ft) No decompression dives
Open Water Diver (OWD)Recreational	Minimum age 10 years Basic swimming ability Medical clearance as required	Recommended max depth 18 m (60 ft) No decompression dives No overhead environment
Advanced AdventurerRecreational	SSI Open Water Diver Minimum age 10 years	Recommended max depth 30 m (100 ft) with Deep Adventure dive No decompression dives
Diver Stress & Rescue (Stress & Rescue)Rescue	SSI Advanced Adventurer Current first aid/CPR/O2 provider	Not a depth rating Focus on prevention and management
Enriched Air Nitrox 40 (EANx40)Specialty	SSI Open Water Diver	Nitrox use up to 40% O2 Plan PPO2 within agency recommendations No decompression unless otherwise qualified
Master Diver (MD)Recreational	SSI Diver Stress & Rescue Four SSI Specialty certifications Minimum 50 logged dives	Recognition rating; no additional depth privileges
Dive GuideProfessional	SSI Diver Stress & Rescue Minimum age 18 years Minimum 40 logged dives Science of Diving or equivalent	May guide certified divers May assist instructors
Deep Diving (Deep)Specialty	SSI Open Water Diver Minimum age 15 years	None listed
Wreck Diving (Wreck)Specialty	SSI Open Water Diver	None listed
Night & Limited Visibility (Night)Specialty	SSI Open Water Diver	None listed
NavigationSpecialty	SSI Open Water Diver	None listed
Search & Recovery (S&R)Specialty	SSI Open Water Diver	None listed
Sidemount Diving (Sidemount)Specialty	SSI Open Water Diver Minimum age 15 years	None listed
Perfect Buoyancy (PPB)Specialty	SSI Open Water Diver	None listed
Dry Suit Diving (Dry Suit)Specialty	SSI Open Water Diver	None listed
Photo & Video (Photo/Video)Specialty	SSI Open Water Diver	None listed
Waves, Tides & Currents (WTC)Specialty	SSI Open Water Diver	None listed
React Right Oxygen ProviderOther	None listed	None listed

NAUI National Association of Underwater Instructors

NAUI certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Scuba Diver (SD)Recreational	Basic swimming ability Medical clearance as required	Recommended max depth 18 m (60 ft) No decompression dives
Advanced Scuba DiverRecreational	NAUI Scuba Diver	Recommended training to 30 m (100 ft) No decompression dives
Rescue Diver (RD)Rescue	NAUI Advanced Scuba Diver Current first aid/CPR	Not a depth rating
Master Scuba Diver (MSD)Recreational	NAUI Rescue Diver Four NAUI specialty certifications Minimum 50 logged dives	Recognition rating
Divemaster (DM)Professional	NAUI Rescue Diver Minimum age 18 years Minimum 50 logged dives Current CPR/First Aid	May supervise certified divers May assist with training
Nitrox DiverSpecialty	Open Water Diver or equivalent	Nitrox up to 40% O2
Deep DiverSpecialty	Advanced-level certification	None listed
Wreck DiverSpecialty	Open Water Diver or equivalent	None listed
Night DiverSpecialty	Open Water Diver or equivalent	None listed
NavigationSpecialty	Open Water Diver or equivalent	None listed

SDI Scuba Diving International

SDI certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Scuba Diver (SD)Recreational	Minimum age 10 years Basic swimming ability Medical clearance as required	Training-level certification Must dive under direct supervision of a professional Maximum depth 12 m (40 ft) No decompression dives
Open Water Scuba Diver (OWSD)Recreational	Minimum age 10 years Basic swimming ability Medical clearance as required	Recommended max depth 18 m (60 ft) No decompression dives
Advanced Adventure DiverRecreational	SDI Open Water Scuba Diver	Recommended max depth 30 m (100 ft) with deep module No decompression dives
Rescue Diver (RD)Rescue	SDI Advanced Adventure Diver Current first aid/CPR/O2 provider	Not a depth rating
Master Scuba Diver (MSD)Recreational	SDI Rescue Diver Four SDI specialties Minimum 50 logged dives	Recognition; no additional depth privileges
Computer NitroxSpecialty	SDI Open Water Scuba Diver	Nitrox use per training (commonly up to 40% O2) Plan PPO2 within agency recommendations
Divemaster (DM)Professional	SDI Rescue Diver Minimum age 18 years Minimum 40 logged dives Current CPR/First Aid	May supervise certified divers May assist with training
Deep DiverSpecialty	SDI Open Water Scuba Diver Minimum age 15 years	None listed
Wreck DiverSpecialty	SDI Open Water Scuba Diver	None listed
Night & Limited Visibility (Night)Specialty	SDI Open Water Scuba Diver	None listed
Underwater Navigation (Nav)Specialty	SDI Open Water Scuba Diver	None listed
Search & Recovery (S&R)Specialty	SDI Open Water Scuba Diver	None listed
Sidemount DiverSpecialty	SDI Open Water Scuba Diver	None listed
Dry Suit DiverSpecialty	SDI Open Water Scuba Diver	None listed
Ice DiverSpecialty	SDI Dry Suit Diver Minimum age 18 years	None listed
Underwater PhotographerSpecialty	SDI Open Water Scuba Diver	None listed

TDI Technical Diving International

TDI certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Intro to TechTechnical	SDI Rescue Diver Buoyancy and equipment proficiency per standards	Skills-focused; does not grant decompression privileges by itself
Advanced Nitrox Diver (AN)Technical	Minimum age 18 years Rescue Diver certification or equivalent Nitrox certification Experience prerequisites per standards	Use of EANx > 40% up to pure O2 for accelerated decompression when combined with DP No staged decompression unless combined with DP
Decompression Procedures Diver (DP)Technical	TDI Advanced Nitrox Diver Deep training/experience per standards	Staged decompression dives within training limits One or more deco gases per standards
Extended Range Diver (XR)Technical	TDI Advanced Nitrox Diver TDI Decompression Procedures Diver	Air/nitrox to deeper ranges with staged decompression Multiple deco gases per standards
Trimix Diver (Normoxic) (TMX)Technical	TDI Extended Range Diver	Normoxic trimix within standards Multiple deco gases
Advanced Trimix Diver (Adv TMX)Technical	TDI Trimix Diver (Normoxic)	Hypoxic trimix per standards for very deep dives Multiple deco gases, complex staging
CCR Air Diluent Diver (CCR Air Dil)Rebreather	Minimum age 18 years Recreational prerequisites per standards Unit-specific requirements	Unit-specific CCR training with air/nitrox diluent Bailout and emergency procedures
Nitrox Diver (Nitrox)Specialty	Open Water Diver or equivalent	Nitrox up to 40% O2 No decompression unless otherwise qualified
Helitrox Diver (Helitrox)Technical	Advanced-level recreational certification Nitrox certification Experience per standards	Helium-based mixes for narcosis management Limited decompression within training
Cavern DiverCave	Advanced-level recreational certification Good buoyancy control	Daylight zone only Linear penetration limits No decompression unless otherwise qualified
Intro to Cave Diver (Intro Cave)Cave	TDI Cavern Diver	Limited penetration distance Simple navigation
Full Cave Diver (Full Cave)Cave	TDI Intro to Cave Diver	Complex navigation permitted Stages and decompression if separately qualified
Sidemount DiverSpecialty	Open Water Diver or equivalent	None listed
Wreck DiverSpecialty	Advanced-level recreational certification	None listed
Advanced Wreck Diver (Adv Wreck)Specialty	TDI Wreck Diver	None listed
CCR Helitrox Diver (CCR Helitrox)Rebreather	TDI CCR Air Diluent Diver	Helitrox diluent for narcosis management Unit-specific
CCR Advanced Mixed Gas Diver (CCR AMG)Rebreather	TDI CCR Helitrox Diver	Advanced trimix CCR diving Complex decompression Unit-specific

CMAS Confédération Mondiale des Activités Subaquatiques

CMAS certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
CMAS One Star Diver () (CMAS )Recreational	Basic swimming ability Medical clearance as required	Autonomous within training and local regulations Typical depth 20 m (national variations)
CMAS Two Star Diver () (CMAS )Recreational	CMAS CMAS One Star Diver (*) Experience per federation	Extended depth training (often to ~30 m) No decompression (unless local federation standards allow training exposures)
CMAS Three Star Diver (*) (CMAS *)Recreational	CMAS CMAS Two Star Diver (**) Rescue/leadership skills per federation	Leadership-level recreational diving within federation rules
CMAS Four Star Diver (**) (CMAS **)Professional	CMAS CMAS Three Star Diver (***) Leadership and instructor prerequisites per federation	None listed

BSAC British Sub-Aqua Club

BSAC certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Ocean DiverRecreational	Club membership Training prerequisites per BSAC	Typical depth 20 m (66 ft) after progression No decompression dives
Sports DiverRecreational	BSAC Ocean Diver	Progressive depth increases (commonly up to 35 m/115 ft with experience sign-offs) Planned decompression techniques via BSAC training pathways
Dive LeaderProfessional	BSAC Sports Diver	Dive management responsibilities within club framework
Advanced DiverRecreational	BSAC Sports Diver	Extended depth and experience
First Class DiverRecreational	BSAC Advanced Diver	High-level recreational and technical skills

RAID Rebreather Association of International Divers

RAID certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Open Water 20 (OW20)Recreational	Basic swimming ability Medical clearance as required	Training to 20 m (66 ft) No decompression dives
Explorer 30Recreational	RAID Open Water 20	Recommended to 30 m (100 ft) with deep module No decompression dives
Decompression Procedures 40 (Deco 40)Technical	Intermediate/advanced recreational training Nitrox and deep training per standards	Limited decompression per course standards One decompression gas
NitroxSpecialty	Open Water Diver or equivalent	Nitrox up to 40% O2
CCR 40Rebreather	Open Water Diver or equivalent Unit-specific prerequisites	CCR with air or nitrox diluent Unit-specific configuration
CCR 60Rebreather	RAID CCR 40	CCR with helitrox diluent Staged decompression
CCR 100Rebreather	RAID CCR 60	Advanced trimix CCR diving Complex decompression
CCR 120Rebreather	RAID CCR 100	Very deep CCR diving with hypoxic trimix Extensive decompression
Trimix 1Technical	RAID Decompression Procedures 40	Normoxic trimix
Trimix 2Technical	RAID Trimix 1	Hypoxic trimix for very deep dives
Cavern DiverCave	Advanced-level recreational certification	Daylight zone only
Intro to CaveCave	RAID Cavern Diver	Limited penetration
Cave 2Cave	RAID Intro to Cave	Complex navigation permitted
Intro to TechTechnical	Advanced recreational certification	None listed

IANTD International Association of Nitrox and Technical Divers

IANTD certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Advanced Nitrox Diver (AN)Technical	Appropriate recreational prerequisites Nitrox training	High-O2 mixes for accelerated decompression when paired with deco training
Normoxic Trimix Diver (Normoxic TMX)Technical	IANTD Advanced Nitrox Diver Decompression training	Normoxic trimix within course limits
Open Water Diver (OWD)Recreational	Basic swimming ability Medical clearance	Recreational limits per IANTD
Nitrox DiverSpecialty	Open Water Diver or equivalent	Nitrox up to 40% O2
Advanced Trimix Diver (Adv TMX)Technical	IANTD Normoxic Trimix Diver	Hypoxic trimix for very deep dives
Cavern DiverCave	Advanced-level recreational certification	Daylight zone only
Intro Cave Diver (Intro Cave)Cave	IANTD Cavern Diver	Limited penetration
Cave Diver (Cave)Cave	IANTD Intro Cave Diver	Complex navigation permitted
CCR Advanced Mixed Gas Diver (CCR AMG)Rebreather	CCR certification Advanced mixed gas experience	Advanced CCR with trimix
Intro to TechTechnical	Advanced recreational certification	None listed
Divemaster (DM)Professional	IANTD Open Water Diver Minimum age 18 years IANTD Rescue Diver or equivalent Logged dives and in-water experience per IANTD standards Current CPR, first aid and oxygen provider training Medical clearance	May supervise certified IANTD divers May assist an instructor with training May not certify divers
Assistant Instructor (AI)Professional	IANTD Divemaster IANTD Divemaster in good standing Assistant Instructor program Current CPR, first aid and oxygen provider training	May teach academic sessions and confined water skills May not certify divers independently
Open Water Instructor (OWI)Professional	IANTD Divemaster IANTD Assistant Instructor IANTD Divemaster or IANTD Assistant Instructor Instructor Development Program and instructor evaluation Current CPR, first aid and oxygen provider training Medical clearance	May teach and certify IANTD divers at the levels each instructor rating covers Technical, cave and rebreather teaching needs the matching instructor rating
Instructor Trainer (IT)Professional	IANTD Open Water Instructor Active IANTD Instructor with the teaching record IANTD requires Instructor Trainer program	May train and certify new IANTD instructors
Assistant Course Director (ACD)Professional	IANTD Open Water Instructor Active IANTD Instructor with the teaching record IANTD requires Assistant Course Director course	May assist with instructor training under a Course Director
Course Director (CD)Professional	IANTD Assistant Course Director IANTD Assistant Course Director Appointment by IANTD	May run IANTD Instructor Development Programs and Assistant Course Director courses

GUE Global Underwater Explorers

GUE certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
GUE Fundamentals (Fundies)Specialty	OWD-equivalent certification Recent diving experience	Not a depth rating; skill and configuration standardization
Tech 1 (T1)Technical	GUE GUE Fundamentals GUE Fundamentals passed at tech rating Experience prerequisites per GUE	Helitrox/trimix as per course standards Staged decompression within course limits
Tech 2 (T2)Technical	GUE Tech 1	Hypoxic trimix dives within course limits Multiple deco gases
Recreational Diver 1 (Rec 1)Recreational	Minimum age per GUE standards Medical clearance	Recreational limits within GUE standards
Recreational Diver 2 (Rec 2)Recreational	GUE Recreational Diver 1	Extended depth training within GUE recreational standards
Recreational Diver 3 (Rec 3)Recreational	GUE Recreational Diver 2	Advanced recreational diving with GUE protocols
Cave 1Cave	GUE GUE Fundamentals GUE Fundamentals passed at tech rating	Limited cave penetration Simple navigation Single tanks or stages per standards
Cave 2 (Cave 2)Cave	GUE Cave 1	Complex navigation Multiple stages DPV use per standards
Apprentice Instructor (AI)Professional	GUE GUE Fundamentals GUE diver certification at or above the level being taught Acceptance onto the GUE instructor apprenticeship Diving and teaching evaluation by a GUE Instructor Trainer	May teach only under the supervision of a qualified GUE instructor Offered for a limited set of courses
Instructor (I)Professional	GUE Apprentice Instructor Completed GUE instructor apprenticeship Passed GUE instructor evaluation GUE diver certification at or above each level taught Active status maintained through teaching and re-evaluation	Teaches only the GUE courses the instructor is rated for, level by level Higher levels (Tech, Cave, CCR) each need their own rating
Instructor Trainer (IT)Professional	GUE Instructor Active GUE Instructor with an established teaching record Appointment by GUE	May train GUE instructor candidates in the courses the rating covers
Instructor Evaluator (IE)Professional	GUE Instructor Active GUE Instructor with an established teaching record Appointment by GUE	May evaluate GUE instructor candidates and instructors

UTD Unified Team Diving

UTD certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Recreational 1 (Rec 1)Recreational	Basic swimming ability Medical clearance	Recreational limits per UTD standards
EssentialsSpecialty	Open Water Diver or equivalent	None listed
Tech 1 (T1)Technical	UTD Essentials	Helium-based mixes Staged decompression

ANDI American Nitrox Divers International

ANDI certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Level 1 — Sport Diver (L1)Recreational	Basic swimming ability Medical clearance as required	Recreational limits per ANDI standards

CDAA Cave Divers Association of Australia

CDAA certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Basic Cave (Basic Cave)Cave	Advanced Open Water recreational certification or equivalent Minimum 50 dives post Open Water Minimum 25 hours bottom time At least 2 night dives and 5 dives deeper than 20 m Minimum age 18 years Successfully complete a diving medical statement	Cavern sites: Maximum depth 20 m, daylight always visible, maximum linear penetration 40 m Sinkhole sites: Large passages (no restrictions too small for two divers adjacent), maximum linear penetration 40 m into overhead areas Recommended maximum depth 40 m on air
Cave Diver (Cave Diver)Cave	CDAA Basic Cave Minimum 20 basic cave dives in at least 2 different sites Minimum 10 hours total bottom time	Enclosed cave environment with overhangs, silt, and darkness zones Passages large enough for two divers to swim adjacent and turn around together Maximum penetration 1/3 of twin cylinder gas supply No complex staged decompression unless separately qualified
Advanced Cave Diver (Advanced Cave)Cave	CDAA Cave Diver	Complex interlinked passages Advanced cave sites with staged decompression requirements Requires appropriate decompression training for staged dives

NSS-CDS National Speleological Society — Cave Diving Section

NSS-CDS certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Cavern DiverCave	Advanced-level recreational certification Buoyancy and guideline skills training per standards	Cavern zone only: daylight zone, within linear/penetration limits per standards No decompression unless otherwise qualified No complex navigation
Intro to Cave Diver (Intro Cave)Cave	NSS-CDS Cavern Diver	Limited penetration distance and simple navigation No complex circuits/siphons unless trained
Full Cave Diver (Full Cave)Cave	NSS-CDS Intro to Cave Diver	Complex navigation permitted within training Stages and decompression only if separately qualified

FFESSM Fédération Française d'Études et de Sports Sous-Marins

FFESSM certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Niveau 1 (Plongeur Encadré 20m) (N1/PE20)Recreational	Minimum age 12 years Medical certificate	Supervised to 20 m or autonomous to 12 m with appropriate certification
Niveau 2 (Plongeur Autonome 20m) (N2/PA20)Recreational	FFESSM Niveau 1 (Plongeur Encadré 20m) Experience per FFESSM	Autonomous to 20 m, supervised to 40 m
Niveau 3 (Plongeur Autonome 60m) (N3/PA60)Recreational	FFESSM Niveau 2 (Plongeur Autonome 20m) Experience and skills per FFESSM	Autonomous to 60 m within French system
Niveau 4 (Guide de Palanquée) (N4/GP)Professional	FFESSM Niveau 3 (Plongeur Autonome 60m) Leadership skills per FFESSM	None listed

AIDA International International Association for Development of Apnea

AIDA International certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
AIDA 1 (AIDA 1)Freediving	Basic water comfort Medical clearance as required	Introductory freediving knowledge/skills
AIDA 2 (AIDA 2)Freediving	AIDA International AIDA 1	Fundamental open water freediving skills and safety
AIDA 3 (AIDA 3)Freediving	AIDA International AIDA 2	Intermediate freediving with deeper capabilities
AIDA 4 (AIDA 4)Freediving	AIDA International AIDA 3	Advanced freediving depths and techniques
AIDA Master (AIDA Master)Freediving	AIDA International AIDA 4	Expert level freediving

Molchanovs Molchanovs Movement

Molchanovs certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Wave 1 (W1)Freediving	Basic water comfort Medical clearance as required	Introductory depth and pool disciplines per standards
Wave 2 (W2)Freediving	Molchanovs Wave 1	Intermediate depth and performance
Wave 3 (W3)Freediving	Molchanovs Wave 2	Advanced freediving
Wave 4 (W4)Freediving	Molchanovs Wave 3	Expert level freediving

Apnea Academy Apnea Academy

Apnea Academy certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Level 1 Freediver (L1)Freediving	Basic water comfort	Entry level freediving

ProTec Professional Technical and Recreational Diving

ProTec certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Extended Range (XR)Technical	Advanced recreational training Nitrox and deco competencies per standards	Deeper dives with staged decompression within ProTec standards

ISE InnerSpace Explorers

ISE certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Technical Foundation (Tech Foundation)Technical	Advanced recreational certification Solid buoyancy/trim	Not a depth rating; skills-based for technical path

SwedTech SwedTech Diving

SwedTech certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Advanced Nitrox (AN)Technical	Nitrox and deep experience per standards	High-O2 mixes for deco when paired with deco training

ERDI Emergency Response Diving International

ERDI certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Public Safety Diver (PSD)Professional	Open Water Diver or equivalent Law enforcement or emergency services personnel	None listed
Underwater Crime Scene Investigator (UCSI)Professional	ERDI Public Safety Diver	None listed
Search and RecoveryProfessional	ERDI Public Safety Diver	None listed
Confined Space DiverProfessional	ERDI Public Safety Diver	None listed

PFI Performance Freediving International

PFI certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Freediver (Freediver)Freediving	Basic water comfort Medical clearance	Entry level freediving
Intermediate Freediver (Int Freediver)Freediving	PFI Freediver	Intermediate freediving
Advanced Freediver (Adv Freediver)Freediving	PFI Intermediate Freediver	Advanced freediving

EFR Emergency First Response

EFR certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Primary Care (CPR) (EFR Primary)Other	None listed	None listed
Secondary Care (First Aid) (EFR Secondary)Other	None listed	None listed
Care for ChildrenOther	None listed	None listed

DAN Divers Alert Network

DAN certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Oxygen ProviderOther	None listed	None listed
Basic Life Support: CPR & AED (DAN BLS)Other	None listed	None listed
First AidOther	None listed	None listed
Diving Emergency Management Provider (DEMP)Other	None listed	None listed

FRTI First Response Training International

FRTI certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
O2 Administration (O2)Other	None listed	None listed

ISC International Scuba Certification

ISC certifications with their category, prerequisites, and limits.
Certification	Prerequisites	Limits
Scuba Diver (SD)Recreational	Minimum age 10 years Medical clearance as required Basic swimming ability	Training-level certification Must dive under direct supervision of a professional Maximum depth 12 m (40 ft) No decompression dives No overhead environment
Open Water Diver (OWD)Recreational	Minimum age 10 years (or 15 for full certification) Basic swimming ability Medical clearance as required	Recommended max depth 18 m (60 ft) No decompression dives No overhead environment
Advanced Open Water (AOWD)Recreational	ISC Open Water Diver Minimum age 12 years	Recommended max depth 30 m (100 ft) for adults, 21 m (70 ft) for 12-14 years No decompression dives No overhead environment
Rescue (RD)Rescue	ISC Advanced Open Water Minimum age 12 years Current CPR/First Aid certification	Not a depth rating Focus on problem prevention and management
Deep DiverSpecialty	ISC Advanced Open Water Minimum age 15 years	Training to dive to 40 m (130 ft) within recreational limits No staged decompression
Wreck DiverSpecialty	ISC Advanced Open Water Minimum age 15 years	External wreck exploration Limited penetration within daylight zone
Divemaster (DM)Professional	ISC Rescue Minimum age 18 years Minimum 40 logged dives to start, 60 to certify Current CPR/First Aid or equivalent Medical clearance within 12 months	May supervise certified divers May assist with training May not conduct courses independently
Assistant Instructor (AI)Professional	ISC Divemaster Minimum age 18 years Minimum logged dives per ISC standards Current CPR/First Aid	May assist instructors with training May not independently certify divers
Open Water Instructor (OWSI)Professional	ISC Assistant Instructor Minimum age 18 years Complete Instructor Development Course Pass Instructor Examination Current CPR/First Aid	May teach and certify divers up to leadership level within certification
Instructor Trainer (IT)Professional	ISC Open Water Instructor Extensive teaching experience Minimum certifications issued per ISC standards Instructor Trainer Course completion	May train and certify instructors
SnorkelerFreediving	Basic water comfort Medical clearance as required	Surface swimming with snorkel No breath-hold diving
Free Diver 5 meters / 16 feet (FD 5m)Freediving	Basic water comfort Medical clearance as required	Maximum depth 5 m (16 ft)
Free Diver 16m/52ft (FD 16m)Freediving	ISC Free Diver 5 meters / 16 feet	Maximum depth 16 m (52 ft)
Advanced Free Diver 24m/79ft (AFD 24m)Freediving	ISC Free Diver 16m/52ft	Maximum depth 24 m (79 ft)
Master Free Diver 32m/105ft (MFD 32m)Freediving	ISC Advanced Free Diver 24m/79ft	Maximum depth 32 m (105 ft)
Snorkel InstructorProfessional	ISC Snorkeler Minimum age 18 years Teaching experience or instructor development Current CPR/First Aid	May teach and certify snorkelers
Freediver InstructorProfessional	ISC Advanced Free Diver 24m/79ft Minimum age 18 years Complete Instructor Development Course Current CPR/First Aid	May teach and certify freedivers up to advanced levels within certification
Freediver Instructor Trainer (FIT)Professional	ISC Freediver Instructor Extensive teaching experience Minimum certifications issued per ISC standards Instructor Trainer Course completion	May train and certify freediving instructors

Guides that use this data

Diving Gases Explained: Air, Nitrox, Trimix, Heliox, Oxygen, and Argon

Understand the breathing and inflation gases divers encounter, what each one does, and why depth and exposure determine whether a mix is suitable.

What is Nitrox? A Complete Guide for Divers

Learn what Nitrox is, how enriched air works, its benefits and risks, and why divers choose it.