A free scuba diving reference: physics, medicine, gear, skills and gases, explained article by article.
Free reference 26 articles in 6 subjects
411 Scuba Diving is a free scuba diving wiki: plain-language articles on how pressure, gas, gear and the human body behave underwater, written for students, new divers and anyone curious about the sport.
Pressure, gas laws, buoyancy and light: the science behind every diving rule.
4 articlesDecompression sickness, narcosis, ears, oxygen toxicity and flying after diving.
5 articlesCompressed air, nitrox and trimix: what's in the tank and why it matters.
3 articlesRegulators, BCDs, dive computers, exposure suits and tanks, explained.
5 articlesBuoyancy, hand signals, buddy checks, safety stops and dive planning.
5 articlesWreck, cave, drift and night diving: what's different and what training you need.
4 articlesFeatured article
The single most important idea in scuba. As you descend, the air in your lungs, ears, mask and BCD is squeezed; as you ascend, it expands again. That simple relationship explains why you never hold your breath on scuba, why your ears hurt on the way down and why the last few metres of every ascent need to be the slowest.
Diving is full of rules: equalize early, never hold your breath, ascend slowly, make a safety stop, wait before you fly. Every one of them has a reason, and most of those reasons come down to a handful of ideas about pressure and gas. This wiki explains those ideas one article at a time, so the rules you learn in a course make sense and stay with you.
Articles are grouped into six subjects. Diving physics covers pressure, gas volume, buoyancy and light. Diving medicine explains decompression sickness, narcosis, ear injuries, oxygen toxicity and flying after diving. Breathing gases compares air, nitrox and trimix. Scuba equipment shows how the regulator, BCD, computer, suit and tank work. Diving skills covers buoyancy, signals, checks and safe ascents. Types of diving looks at wrecks, caves, drift and night dives.
Every article opens with a short summary and a quick-facts box, gives metric and imperial units, and links to the related articles you'll want next. Each one ends with answers to common questions. The glossary defines the terms divers use, from absolute pressure to yoke valve, and the A–Z index lists every article in one place.