I have never had a serious diving accident. I want to be careful about how I say that, because it could be read as smugness, and it isn’t meant that way. The more accurate statement is: I have never had a serious diving accident yet, and the gap between those two sentences is where all of diving safety lives.
The divers I know who are most rigorous about planning and safety are, without exception, the most experienced divers I know. This is not a coincidence. Experience teaches you how small the margins can get, and how quickly a dive that was proceeding normally can become a dive that isn’t.
The Basics That Stay Basics
The fundamentals of safe recreational diving are taught in every Open Water course and remain relevant on your five hundredth dive:
Never hold your breath. This is the single most important rule in scuba diving. As you ascend, the air in your lungs expands due to decreasing pressure. If you hold your breath during an ascent, that expanding air has nowhere to go. The result is a pulmonary barotrauma — an overexpansion injury to the lungs — that can be immediately life-threatening. Breathe continuously. Always.
Ascend slowly. The standard recreational ascent rate is 9 metres per minute or slower. Ascending too quickly doesn’t allow dissolved nitrogen to leave your tissues gradually, which increases the risk of decompression sickness. Most dive computers display your current ascent rate and will alarm if you exceed the safe limit. Pay attention.
Make a safety stop. A three-to-five minute stop at five metres at the end of every dive — not just dives that approach no-decompression limits — provides a buffer for nitrogen off-gassing and is best practice regardless of your dive profile. It also gives you a moment to get your buoyancy sorted before the final ascent.
Plan your dive, dive your plan. Know your maximum depth, your turn-around pressure, and your ascent timing before you enter the water. Communicate these to your buddy. Stick to them.
The rule of thirds. For dives in overhead environments or where the return route requires air: use one-third of your air supply for the outward journey, reserve one-third for the return, and keep one-third in reserve for emergencies. In open-water recreational diving, a simpler version applies: turn the dive and begin ascending when you reach 100 bar, ensuring you surface with at least 50 bar remaining.
Understanding Decompression Sickness
Decompression sickness (DCS, also called “the bends”) occurs when nitrogen that has dissolved in body tissues under pressure forms bubbles as external pressure decreases too quickly during ascent. The bubbles can form in joints, causing pain; in the spinal cord, causing neurological symptoms; in the lungs, causing respiratory distress; or in the brain, causing stroke-like symptoms.
Mild DCS — joint pain, skin rash, fatigue — can develop hours after a dive. Serious DCS requires immediate treatment in a hyperbaric (recompression) chamber, where the diver is exposed to increased pressure to re-dissolve the nitrogen bubbles, then slowly brought back to surface pressure at a controlled rate.
Risk factors for DCS include diving to depth frequently over multiple days (cumulative nitrogen loading), ascending too quickly, flying within 12 to 24 hours of diving, dehydration, heavy exertion immediately after diving, and individual physiological factors including patent foramen ovale (a hole between the upper chambers of the heart, present in about a quarter of adults, that allows bubbles to bypass the lungs and enter arterial circulation directly).
The practical implications: follow your dive computer’s no-decompression limits and surface interval recommendations, stay well hydrated, avoid flying for at least 12 hours after a single recreational dive and 18 hours after multiple dives or deep dives, and do not exercise vigorously immediately after diving.
Dive Computers and How to Use Them
The dive computer is the most important piece of safety equipment a recreational diver carries. It continuously monitors depth and time, calculates your nitrogen loading using a decompression algorithm, and displays your remaining no-decompression time — the amount of time left at your current depth before you would need to perform decompression stops to ascend safely.
Modern recreational dive computers are generally conservative and generally reliable. “Generally” is the operative word. Computers are models of physiological processes, not measurements of what’s actually happening in your body. They can be configured more or less conservatively (most allow you to set a personal conservatism factor), and more conservative settings produce shorter no-decompression limits and longer surface interval recommendations. If you’re diving multiple days in a row, on liveaboards, or at altitude, more conservative settings are appropriate.
Read the manual for your specific computer. Know what the alarms mean. Know how to read the nitrogen loading display, not just the remaining bottom time.
Planning Multi-Day Dive Trips
Cumulative nitrogen loading across multiple diving days is something new divers underestimate. On day one of a liveaboard, your no-decompression limits will be those the computer calculates fresh. By day three of four-dives-a-day diving, your residual nitrogen from previous dives will be constraining how long and how deep you can go on each subsequent dive.
This is normal and manageable, but it requires attention. The most common mistake I see on liveaboards is divers who do four dives on day one without adequate surface intervals, find their computer increasingly conservative on days two and three, and end up frustrated or — worse — tempted to push limits that exist for good reasons.
Adequate surface intervals (usually 60 minutes minimum between dives, longer between the day’s final dive and the next morning’s first), good hydration, and avoiding alcohol between diving days are all practical risk reducers on multi-day trips.
What to Do When Something Goes Wrong
The most important thing to do when a dive is not going according to plan is to slow down, breathe, and communicate. Most diving emergencies begin as manageable situations that escalate because someone panicked and made rapid decisions.
If your regulator free-flows: breathe from the corner of your mouth rather than sealing your lips around the mouthpiece, signal your buddy, and ascend at a controlled rate.
If you’re low on air: signal your buddy immediately with the low-air signal (fist to chest), begin a controlled ascent while your buddy provides buddy breathing or donates their alternate air source if necessary.
If you feel unwell underwater: signal your buddy, ascend slowly to shallower water, and communicate your symptoms to the dive guide on the surface.
If you suspect DCS after a dive: lie down, breathe pure oxygen from an emergency oxygen kit if available, hydrate, and seek medical attention immediately. Call DAN (Divers Alert Network) — in Australia the number is 1800 088 200. Do not wait to see if symptoms resolve on their own.
Diving safety isn’t anxiety. It’s the thing that makes continued diving possible.
