What goes wrong on a typical recreational dive — and what to do

The 10 things that actually happen

Walk into any dive shop bar and listen to divers debrief. The conversations are not about sharks or out-of-air situations. They are about leaky masks, ear pops, calf cramps, and that one moment when the regulator made a funny noise. Almost every dive contains a tiny inconvenience that, with training, gets ignored.

Here is the honest frequency ranking, drawn from dive log surveys, instructor reports, and our own count across hundreds of trips through Thailand and Indonesia:

The takeaway from this table is the right-hand column. Most things on this list never lead to aborting the dive. The two exceptions — buddy separation and free-flow — have well-rehearsed protocols.

How often each one actually happens

The proportions matter. A diver who has done 50 dives has experienced numbers 1–4 dozens of times. They’ve probably had number 5 on a rough morning. They’ve definitely had numbers 6 and 7. They’ve had a moment of buddy separation that ended fine. They likely have a small scar from coral on their knee. They’ve probably never seen a free-flow.

The fixes, in detail

1. Mask leak or partial flood

Water comes in through a hair caught under the seal, a smile that breaks the silicone contact, a kick from a passing fin. It is the most common in-water issue and the easiest to fix.

Drill:

1. Stop kicking. Stabilise.
2. Tilt your head slightly back (look up, not straight up).
3. Press the top frame of the mask firmly against your forehead with one hand.
4. Exhale slowly through your nose for 2–3 seconds.
5. The water drains out the bottom of the skirt as air pushes from the top.

A full mask flood clears in one or two breaths if the seal is good. If your mask leaks repeatedly, the issue is usually fit (try a different model on the boat) or hair caught in the skirt (tuck it back at the surface).

2. Ear equalization problem

The first 5 metres of any descent involve equalising your middle ear with ambient pressure. Most divers do this with the Valsalva manoeuvre — pinch your nose and gently blow against it. Some prefer Frenzel or other techniques.

When it doesn’t work:

1. Stop descending. Ascend 1 metre.
2. Try equalising again, gently. Don’t force it.
3. If still no equalisation, ascend another metre.
4. If still nothing, signal your buddy and surface together. Try again on a slow re-descent.

Never force ear pressure. A burst eardrum from aggressive Valsalva is the kind of injury that ends your dive trip and your week. If equalising isn’t working today — congestion from a cold, sinus issue, allergies — sit out the dive. There will be other dives.

A separate guide covers ear equalisation in detail. Read it if you have repeated issues.

3. Mask fogging

Plastic and silicone masks fog when warm exhaled breath hits the cold inside of the lens. Defogging on the surface and during the dive solves it.

Pre-dive:

• Spit in the dry mask, rub the saliva into both lenses, rinse lightly. Old-school but effective.
• Or use anti-fog spray (Sea Drops, Stream2Sea, etc., ~$5).
• For a brand new mask, scrub with toothpaste once to remove the factory silicone film. Otherwise nothing else will work.

Mid-dive:

• Crack the bottom skirt, let a small amount of water in, swish around the lens, clear the mask.
• This essentially re-rinses the lens.

A fogged mask is annoying but not dangerous. Practise the in-water clearing technique so you don’t think about it.

4. Buoyancy struggle

This is the universal new-diver problem. Too much weight makes you sink and over-inflate the BCD to compensate. Bad trim makes you kick sideways. Floating up unintentionally near the safety stop happens to almost everyone in their first dozen dives.

Mid-dive fix:

1. Stop moving.
2. Find neutral buoyancy by adjusting BCD with small puffs of air or release.
3. Match your breathing to your depth — inhale to rise slightly, exhale to drop slightly.
4. Streamline your body — horizontal, fins level with hips, arms close to torso.

Long-term fix:

• Get reweighted by an honest instructor. Most divers are overweighted.
• A proper weight check at the surface: with a full breath you should float at eye level with an empty BCD.
• Take a Peak Performance Buoyancy specialty if it keeps being a problem.

5. Sea sickness on the boat

The boat ride to the dive site is where most sea sickness happens. Once you’re in the water, motion stops, and most queasiness fades.

Prevention:

• Eat a light, dry breakfast (toast, banana). Empty stomach is worse than light meal.
• Stay on deck, look at the horizon, fresh air.
• Stugeron / Cinnarizine (Asia) or Bonine / meclizine (US) the night before and morning of. Avoid drowsy formulas.
• Sea-bands (pressure-point wristbands) help some people, placebo for others.
• Stay hydrated but don’t chug water on the boat.

Acute:

• If you’re going to be sick, do it over the side of the boat, downwind.
• Tell the crew — they have buckets and seen it all.
• Most people feel better immediately after the dive itself.

6. Calf or foot cramp

Almost always caused by overworked calf muscles, mild dehydration, or fins that don’t fit well. Happens often, fixes in 30 seconds.

In-water fix:

1. Stop kicking.
2. Grab the tip of the cramping fin and pull it slowly toward your shin (stretching the calf).
3. Hold for 10–20 seconds.
4. Resume kicking with a slower cadence.

Hydrate before dives. If cramps are persistent, check fin fit and consider lighter open-heel fins (Mares Avanti, Atomic Aquatics, ScubaPro Seawing).

7. Dry mouth from the regulator

Regulators deliver dry air. After 40 minutes of dry breathing through a rubber mouthpiece, your tongue is sandpaper. It is universal and not dangerous.

Fix:

• Drink water on the surface interval — a full litre between dives.
• Carry a small spare water bottle. Sip after the regulator comes out.
• For very long dives, suck slightly on the mouthpiece to stimulate saliva. Don’t bite.

8. Buddy separation

Lost-buddy protocol is part of every Open Water course. The standard rule:

1. Search for your buddy for one minute at your current depth, slowly turning a full 360 degrees and looking up.
2. If you do not find them in one minute, surface — slowly, with a safety stop if depth allows.
3. On the surface, look around. They should be doing the same thing.
4. Reunite, brief, decide whether to re-descend or end the dive.

The reason for the one-minute rule: searching at depth wastes gas and can lead to deeper trouble. Surfacing is the safer reset.

Some instructors disagree on the safety stop in a buddy-separation scenario — if you have plenty of gas and a normal profile, do it; if the situation is degenerating, skip it. Use judgment.

9. Free-flowing regulator

The second stage sticks open and dumps gas continuously. Often caused by very cold water, grit in the demand valve, or a damaged seat.

Drill:

1. Hold the mouthpiece loosely between your teeth (don’t bite).
2. Sip from the gas that flows past — you still get air, just with bubbles.
3. Signal your buddy with the “trouble here” wobble.
4. Begin a controlled ascent.
5. At the surface, switch to the snorkel or breathe normally.

A free-flowing regulator empties a 200-bar tank in roughly 2–3 minutes at depth. So this is a time-limited problem requiring a relatively prompt ascent, but it is not a sudden out-of-air scenario.

10. Coral scrape or jellyfish sting

Brushing fire coral, scraping a knee on a wreck, getting hit by a hydroid tentacle, finding the tail of a stonefish with your wetsuit — all common, all minor in nearly every case.

On-boat treatment:

• Coral / fire coral / hydroid sting: rinse with vinegar (most dive boats carry it). Avoid fresh water — it activates remaining nematocysts. Apply hydrocortisone if you have it.
• Jellyfish sting (most species in tropical Asia): vinegar rinse, antihistamine, observe.
• Box jellyfish (rare, dangerous): vinegar, immediate medical attention.
• Coral scrape: clean with antiseptic, monitor for infection. Tropical scrapes often get infected — use antibiotic ointment.
• Sea urchin spine: leave most spines in (they dissolve in 2–3 weeks), pull out only the easy ones, monitor for infection.

A small first aid kit on your trip should include: vinegar, antihistamine (oral and cream), hydrocortisone cream, antibiotic ointment, plasters/Band-Aids, vinyl gloves, sterile gauze. The boat will have the basics; your kit covers the gaps.

What is on every “what can go wrong” list that isn’t actually common

Worth flagging the rare things that get airtime out of proportion to their frequency:

• Shark attacks on divers. Extraordinarily rare. About 1 unprovoked incident per multiple millions of dives globally. Most dives that encounter sharks are uneventful — the shark leaves.
• Whale strikes. Even rarer than shark incidents. Whales avoid divers.
• Equipment catastrophic failure. Modern regulators almost never fail in a way that creates a sudden problem. They free-flow (manageable) or develop slight leaks (visible).
• Tanks bursting. Tanks are tested every 5 years (hydro) and inspected annually (VIP). Failures are vanishingly rare and almost always happen during filling at the shop, not at depth.
• Currents pulling you out to sea. Strong currents are a real consideration but the modern fix is dive planning — most operators don’t drop divers into currents they can’t manage. Drift dives are intentional, the boat picks you up downstream.

These do happen. They are not in the top 10 because they almost never happen.

The actual ranking of severity (vs frequency)

Frequency and severity don’t correlate. Most common problems are trivial; least common problems can be serious. To map this out:

• High frequency, low severity: mask issues, fog, dry mouth. The boring background of every dive.
• Medium frequency, medium severity: ear problems, buoyancy struggle, cramping. Trained for, occasionally trip-affecting.
• Low frequency, medium severity: buddy separation, sea sickness severe enough to skip, free-flow.
• Very low frequency, high severity: out-of-air at depth (preventable), decompression sickness, panic-driven emergencies. Distinct articles cover each.

If you internalise the top 10, you’ve covered roughly 99% of what you’ll deal with across hundreds of dives.

How training maps to each problem

The reason Open Water training feels repetitive in confined water is that the drills cover this exact list:

• Mask flood / clear: mask issues
• Regulator recovery: lost mouthpiece, dry mouth recovery
• Buoyancy check / fin pivot: buoyancy struggle
• Out-of-air signal + octopus share: out-of-air, free-flow
• CESA: lost buddy at depth with no air
• Buddy buoyancy check on surface: weight problems
• Underwater navigation: separation prevention
• Surface tow: helping a tired diver

Skip any of these in your course and the corresponding real-world problem is harder. Push back if your instructor wants to compress training — the drills are the entire point.

When to actually abort a dive

There is no shame in calling a dive. Most experienced divers call dives more often than new divers — they know the trigger conditions.

Abort signals (yours or your buddy’s), worth respecting immediately:

• Persistent ear pain after multiple attempts to equalise
• Equipment that isn’t behaving (regulator, BCD, computer)
• Anxiety that won’t settle after a STOP/THINK/ACT pause
• Stronger-than-briefed current
• Cold beyond your comfort
• Gas consumption higher than planned
• Anything you can’t articulate but you know is wrong

The dive will be there tomorrow. So will the better conditions, the better gear, the rested version of you. Aborting is a skill, not a failure.

Bottom line

A typical recreational dive contains 2–3 minor annoyances and zero real problems. Across a year of frequent diving you’ll have one moment that required a trained response — a free-flow, a buddy separation, a serious cramp. The training will handle it.

The mental model worth carrying:

1. Most things that “go wrong” are inconvenient, not dangerous.
2. Every common problem has a trained drill that takes 30 seconds or less.
3. The rare-but-serious problems all have responses you’ve practised.
4. Calling a dive is a feature, not a failure.

Scuba diving is statistically safer than most adventure sports — Open Water diving runs about 1 fatality per 200,000 dives. The reason is not luck. It is that divers train for this exact list of problems and the training works.