Diving guides that do the math

Scuba Cylinders Explained: Sizes, Materials, and Buoyancy

What cylinder labels really mean, how working pressure sets the gas you carry, and why aluminum, steel, and composite cylinders behave differently in the water.

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.

Nitrox Blending: Oxygen, Air, and Residual Gas

Learn how partial-pressure and continuous Nitrox blending account for residual gas, and why every calculated fill must still be analyzed.

Pressure and ATA Basics for Scuba Divers

Build the pressure foundation behind gas use, partial pressure, buoyancy, and decompression with worked metric and imperial examples.

Scuba Diving Units: Bar, PSI, Meters, and Feet

Convert the units divers use, understand which conversions are exact or approximate, and avoid mixing pressure, depth, and cylinder capacity.

Turn Pressure and the Rule of Thirds

Calculate a usable turn pressure, distinguish thirds from minimum gas, and choose the earlier limit for direct-ascent and return-to-exit dives.

Rock Bottom Gas: How Much Reserve Do You Really Need?

Calculate minimum gas for a two-diver emergency ascent and learn how depth, breathing rate, and cylinder size change reserve pressure.

How Long Will My Scuba Tank Last?

Estimate cylinder duration from usable gas, depth, and RMV, and understand why a constant-depth estimate is not a complete dive plan.

Understanding SAC Rate: Why It Matters for Every Diver

Learn what Surface Air Consumption rate is, how to calculate it, and tips to improve your breathing efficiency underwater.

SAC Rate vs RMV: What's the Difference and When to Use Each

Understand the difference between SAC rate and RMV, when to use each metric, and how to convert between them.

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.

CNS Percentage and OTU: Tracking Oxygen Exposure

Learn how the CNS clock and OTU loading track oxygen exposure across a dive and a diving day, and what the limits mean.

Nitrox Blending: Oxygen, Air, and Residual Gas

Learn how partial-pressure and continuous Nitrox blending account for residual gas, and why every calculated fill must still be analyzed.

Equivalent Air Depth (EAD) Explained

Work out the air depth a Nitrox dive is decompression-equivalent to, and see why EAD never changes your oxygen limit.

Best Nitrox Mix for Any Depth

Calculate the richest theoretical Nitrox mix for a planned depth and PPO2 limit, then learn how to apply the result safely.

Understanding MOD: Maximum Operating Depth Explained

Learn what Maximum Operating Depth means, how MOD is calculated from oxygen percentage and PPO2 limits, and how to apply it in real dive planning.

Diving Safety: Essential PPO2 Limits Every Diver Should Know

Understand partial pressure of oxygen limits, oxygen toxicity risks, and how to stay safe at depth.

No-Decompression Limits and Safety Stops

Learn what an NDL represents, compare modelled air and Nitrox limits, and understand how ascent rate and safety stops fit into the plan.

Surface Intervals and Repetitive Dives

Understand residual nitrogen between dives, how surface intervals restore no-stop time, and the rules for flying after diving.

Equivalent Air Depth (EAD) Explained

Work out the air depth a Nitrox dive is decompression-equivalent to, and see why EAD never changes your oxygen limit.

Scuba Cylinders Explained: Sizes, Materials, and Buoyancy

What cylinder labels really mean, how working pressure sets the gas you carry, and why aluminum, steel, and composite cylinders behave differently in the water.

Weighting and Buoyancy Control

Find a weighting that lets you hold a stop at the end of a dive, and understand why cylinders and suits change the answer.

Nitrogen Narcosis: Signs and Management

Understand what causes narcosis, calculate trimix END under an explicit convention, and learn the habits that keep impairment manageable.

Pressure and ATA Basics for Scuba Divers

Build the pressure foundation behind gas use, partial pressure, buoyancy, and decompression with worked metric and imperial examples.

Scuba Diving Units: Bar, PSI, Meters, and Feet

Convert the units divers use, understand which conversions are exact or approximate, and avoid mixing pressure, depth, and cylinder capacity.

Scuba Buddy Checks and Predive Safety

Turn the familiar buddy check into a practical team briefing covering gas, releases, weights, computers, route, limits, and emergencies.