Scuba diving safety

Is scuba diving safe?

Short answer: for trained divers who stay within their training and follow the basic rules, recreational diving has a good safety record.

Most serious diving incidents trace back to a short list of causes: running low on air, ascending too fast, diving beyond your training or comfort, diving with a medical condition that should have been checked, or equipment that was not checked before the dive. Every one of those can be managed with the habits below.

What is the most important rule in scuba diving?

Short answer: breathe continuously and never hold your breath.

Air in your lungs expands as you rise because the water pressure around you drops. If you hold your breath while ascending, even a few metres, that expanding air can overexpand and injure the lungs, and in the worst case push air bubbles into the bloodstream (an arterial gas embolism). Breathing slowly and normally the whole time keeps the airway open so expanding air escapes on its own. It is the first rule taught in every course for good reason.

How do I equalize my ears?

Short answer: start before you descend, equalize every metre or so, and never force it.

As you go down, water pressure pushes on your eardrums. You balance it by moving a little air into the middle ear. The most common method is to pinch your nose through the mask and blow gently against it; swallowing or wiggling your jaw also works for many people. Equalize at the surface, then little and often on the way down, before you feel discomfort. If an ear will not clear, rise a metre or two and try again. Never keep descending with pain, and do not dive with a cold or congestion, which can block the passages and cause ear or sinus injuries.

How fast should I ascend, and what is a safety stop?

Short answer: no faster than 9 metres (30 feet) per minute, with a three-minute stop at about 5 metres (15 feet).

While you dive, your body absorbs extra nitrogen from the air you breathe. A slow ascent lets it leave your tissues gradually through your lungs instead of forming bubbles. Most training agencies and dive computers use a maximum ascent rate of 9 metres per minute, and slower is better near the surface where pressure changes fastest. The safety stop, three minutes at around 5 metres, is recommended at the end of every dive even when it is not strictly required. Your dive computer will show the rate and time the stop for you.

What is decompression sickness?

Decompression sickness (DCS), sometimes called "the bends", happens when dissolved nitrogen forms bubbles in the body after a dive. Symptoms can include joint pain, unusual tiredness, numbness or tingling, a skin rash, dizziness or weakness, and they usually appear within a few hours of surfacing. Staying within no-decompression limits, ascending slowly, making safety stops and staying hydrated all lower the risk.

If you suspect DCS, treat it as an emergency: give the diver 100% oxygen if it is available, contact emergency services, and call a diving emergency hotline such as the one run by Divers Alert Network (DAN). Treatment is usually in a hyperbaric (recompression) chamber, and early treatment gives the best outcome.

How long should I wait to fly after diving?

Short answer: at least 12 hours after a single dive, and at least 18 hours after several dives or several days of diving.

Aircraft cabins are pressurized to the equivalent of a mountain altitude, so flying too soon after diving raises the risk of DCS. Divers Alert Network recommends a minimum surface interval of 12 hours after a single no-decompression dive, 18 hours after multiple dives per day or multiple days of diving, and substantially longer after dives that needed decompression stops. Many divers simply plan a full day without diving before a flight. The same caution applies to driving over high mountain passes after a dive. Build this into your plans when you book a scuba diving trip.

What is a buddy check?

Before every dive, you and your buddy check each other's equipment. One common memory aid is BWRAF: BCD (it inflates and deflates), Weights (in place and releasable), Releases (you know how every buckle and strap opens), Air (the tank valve is fully open, the gauge reads full and both second stages breathe properly) and Final OK (mask, fins and computer ready). It takes a minute and catches most of the equipment problems that cause trouble underwater. Agree on hand signals, a maximum depth and time, and what pressure you will turn the dive at.

Can I dive with a medical condition?

Some conditions are compatible with diving and others are not, and the answer often depends on the details. Training agencies use a standard medical questionnaire; any "yes" answer means a doctor must review your fitness to dive and sign a form. Diving medicine specialists and DAN's medical information line can help your doctor with the specifics. Never hide a condition to get onto a course or a boat.

What is nitrogen narcosis?

Breathing nitrogen under pressure has a mild intoxicating effect. Many divers start to notice it at around 30 metres (100 feet), and it gets stronger with depth. It can slow your thinking and make you overconfident. The effect clears as soon as you ascend a little, which is one reason recreational dives stay shallow. Depth training is part of the advanced course covered in learning to scuba dive.