Divers protect themselves by managing their ascent rate, maintaining their equipment, staying within depth and time limits, and planning for emergencies before they get in the water. Drowning is the leading cause of diving fatalities, and the most common trigger in fatal incidents is running out of breathing gas. Nearly every serious diving accident involves a chain of preventable errors rather than a single catastrophic failure, which means safety comes down to habits, not luck.
Control Your Ascent Rate
Rising too quickly is one of the most dangerous things a diver can do. As you ascend, the water pressure around you drops, and dissolved nitrogen in your blood and tissues expands into bubbles. If you ascend faster than your body can safely off-gas that nitrogen, you risk decompression sickness.
The U.S. Navy and NOAA recommend ascending no faster than 30 feet per minute. Recreational training agencies allow rates between 30 and 60 feet per minute, but slower is generally safer. A good rule of thumb: rise no faster than your smallest bubbles. Most dive computers will warn you if you’re ascending too quickly.
At the end of every dive, make a safety stop at about 15 feet for three to five minutes. This pause happens in the shallow zone where pressure changes are greatest, giving your body extra time to release nitrogen before you reach the surface. Safety stops are technically optional on no-decompression dives, but they significantly reduce your risk and should be treated as standard practice.
Respect Your No-Decompression Limits
Every combination of depth and time produces a specific nitrogen load in your body. Stay within no-decompression limits and you can ascend directly to the surface (at a safe rate) without mandatory decompression stops. Exceed those limits and you’re committed to staged stops on the way up, with serious consequences if you skip them.
Modern dive computers calculate your nitrogen load in real time, adjusting for your actual depth profile rather than assuming you spent the entire dive at maximum depth. They use mathematical models with built-in safety margins, and many let you increase the conservatism further through gradient factor settings. If you’re diving at altitude, in cold water, or feeling fatigued, dialing up that conservatism is a smart move. Your computer is a tool, not a guarantee. It models average physiology, and your body on any given day may not be average.
Watch for Nitrogen Narcosis
Breathing air at depth produces a narcotic effect that feels like mild alcohol intoxication. Some divers notice impaired judgment and fuzzy thinking as shallow as 100 feet (30 meters), and every diver is significantly affected by 200 to 230 feet (60 to 70 meters). The earliest symptoms hit your higher-level thinking first: judgment, reasoning, short-term memory, and concentration. You may feel euphoric and confident at exactly the moment your decision-making is compromised.
Go deeper and the effects worsen into poor coordination, fixation on a single idea, hallucinations, and eventually unconsciousness. The fix is simple: ascend. Narcosis clears rapidly as you move to shallower water. Recreational divers staying above 130 feet (40 meters) are far less likely to encounter serious impairment, but susceptibility varies from person to person and even dive to dive. If something feels off at depth, go up.
Check Your Air and Maintain Your Gear
Running out of breathing gas is the single most common trigger in fatal diving accidents. Check your pressure gauge frequently throughout every dive, not just when you remember. Agree on a turn-pressure with your buddy before the dive, and stick to it. Many divers use the “rule of thirds,” reserving one third of their gas for the trip out and one third as a safety margin.
Your regulator should be professionally serviced every year or every 100 dives, whichever comes first. Your tank needs a visual inspection annually for corrosion, dents, and valve damage, plus hydrostatic testing every three to five years depending on the cylinder type and local regulations. Between professional services, rinse your regulator in fresh water after every dive, check for free-flowing or unusual breathing resistance, and visually inspect O-rings and hoses for cracks.
Use a Surface Marker Buoy
A surface marker buoy (SMB) is an inflatable tube you send up on a line from depth to mark your position for the boat. Deploying one at the start of your ascent lets the boat crew see exactly where you are while you complete your safety stop. Without one, you surface as a small head in open water, sometimes far from where the boat expects you, which creates a real risk of being struck by a propeller or lost at the surface.
Carry at least 50 percent more line on your reel than the depth you’re diving. Before inflating, look up to make sure no divers are directly above you and the boat isn’t already overhead. Use only a small puff of gas to fill the SMB initially so it doesn’t rocket upward and drag you with it. Your buddy should watch you during deployment with a cutting tool ready in case the line tangles. As you ascend, keep tension on the line by reeling in slack so the buoy stays upright and visible.
Know the Signs of Decompression Sickness
Decompression sickness (DCS) can appear within minutes of surfacing or take several hours to develop. The symptoms range from mild to life-threatening and include joint pain (the most classic sign), numbness or tingling, unusual fatigue, dizziness, skin mottling, weakness, and difficulty with coordination. In severe cases, divers experience paralysis, loss of bladder or bowel control, personality changes, difficulty breathing, or collapse.
If you suspect DCS in yourself or a dive buddy, the immediate priority is 100% oxygen. Surface-level oxygen given as first aid can relieve symptoms and should be started as soon as possible. Keep the person lying flat, hydrated, and calm while arranging emergency evacuation to a facility with a recompression chamber. Contact the Divers Alert Network emergency hotline, which operates 24/7 worldwide, for guidance on the nearest treatment facility. Do not re-enter the water to attempt “in-water recompression” unless you have specific training and equipment for it.
Wait Before You Fly
Cabin pressure on a commercial aircraft is equivalent to being at 6,000 to 8,000 feet of altitude. If you still have excess nitrogen in your tissues from diving, that reduced pressure can trigger decompression sickness in the air. The recommended surface intervals before flying depend on your dive profile:
- Single no-decompression dive: wait at least 12 hours
- Multi-day or repetitive diving: wait at least 18 hours
- Dives requiring decompression stops: wait substantially longer than 18 hours
DAN’s simplified recommendation is to wait a full 24 hours after any recreational diving. This is a sensible default, especially since the research behind these guidelines was conducted with resting subjects in dry chambers. Real-world diving involves exercise, cold water, and other stressors that may slow nitrogen elimination. If your vacation schedule is tight, plan your last dive for the second-to-last day rather than cutting the surface interval short.
Address Health Risks Honestly
Pre-existing heart conditions are a major factor in diving deaths. In DAN’s analysis of 2019 fatalities, heart disease or acute cardiac events accounted for roughly a fifth of diver deaths. Coronary artery disease, high blood pressure, and a condition called diastolic dysfunction (where the heart doesn’t relax properly between beats) all increase risk. Diastolic dysfunction is common in middle-aged adults and often produces no obvious symptoms on land, but the cardiovascular demands of diving can expose it.
A thorough dive medical exam is worth the investment, especially if you’re over 40, have a history of high blood pressure, or haven’t been assessed in several years. Fitness matters, too. Divers who can handle moderate exertion without becoming winded are far better equipped to manage current, surface swims, and the physical work of dealing with an unexpected problem underwater. Fatigue and overexertion contribute to the same chain of events that leads to drowning: increased air consumption, panic, and poor decision-making at the worst possible moment.
Dive With a Buddy and a Plan
Before every dive, agree on a maximum depth, turn time or turn pressure, and what to do if you get separated. Run through hand signals and confirm that both of you know where the ascent line or exit point is. Check each other’s gear: confirm the air is on, the BCD inflates and deflates, weight release mechanisms work, and alternate air sources are accessible.
Stay close enough to reach your buddy in a few seconds. A buddy 50 feet away might as well be solo if something goes wrong. True buddy diving means maintaining visual contact, checking in regularly, and being genuinely prepared to share air and manage an emergency ascent together. If you prefer diving independently, get proper solo diving training and carry redundant gas and buoyancy systems. Half-committed buddy diving, where you’re nominally paired but functionally alone, is the worst of both approaches.