Freediving and Flying: How Long Should You Wait?

There’s no single, agreed rule for freediving and flying like the published guidelines for scuba divers. After a few relaxed, shallow dives, many instructors consider the risk of flying low. After a day of deep, repetitive freediving with short rests, the conservative choice is to wait at least 24 hours before flying or driving up into the hills. If you also went scuba diving, follow the scuba guidelines. When you’re unsure, ask your instructor or a diving medicine service such as DAN.

Why flying matters after any kind of diving

An airliner cabin is pressurised, but not to sea level. On a typical flight, the cabin pressure is roughly what you’d experience at 1,800 to 2,400 metres above sea level. That lower pressure makes any nitrogen dissolved in your tissues more likely to come out of solution as bubbles, which is how decompression sickness (DCS) happens.

Scuba divers breathe compressed air for long periods, so they absorb a lot of nitrogen, and the flying rules were written for them. Freedivers take one breath at the surface for each dive, so the amount is much smaller. Much smaller is not zero, though.

Can freedivers absorb enough nitrogen to matter?

On each dive, the air in your lungs is compressed and some of its nitrogen dissolves into your blood and tissues. On a single dive the amount is small. Over many dives to depth with short rests, it can build up faster than your body clears it. That’s how breath-hold divers get decompression sickness, sometimes called taravana. Our post on decompression sickness in freediving covers the history and the surface interval rules of thumb.

The factors that raise the risk are the same ones that matter for DCS in general: depth, number of dives, length of each dive, short surface intervals and long sessions. Dehydration and exhaustion probably don’t help either, and both are easy to slip into on a hot boat day off the Indian coast.

What the guidelines say: scuba vs freediving

For recreational scuba, the guidelines most dive centres follow come from a 2002 DAN workshop. They suggest waiting at least 12 hours after a single no-decompression dive, at least 18 hours after multiple dives in a day or multiple days of diving, and substantially longer than 18 hours after dives that needed decompression stops. Some operators simply round this up to 24 hours.

Freediving has no agreed equivalent. Depending on who you ask, advice ranges from no particular wait after recreational dives to 12 to 24 hours after deep training days. The evidence behind any specific number is thin, which is exactly why we lean conservative.

A conservative plan for your last diving day

This is our conservative suggestion, not an official standard. Where sources disagree, we’ve taken the cautious end.

What you did	Before flying or driving to altitude
A few relaxed, shallow dives with long rests	Low risk; leaving a few hours and flying rested and hydrated is easy insurance
Depth training: several dives beyond about 20 metres with normal rests	Wait 12 to 24 hours; choose 24 if you can
Long sessions of repeated dives to depth with short rests, spearfishing days or maximum attempts	Wait at least 24 hours
Any scuba diving in the same period	Follow the scuba guidelines above
Any symptom of DCS, lung squeeze or ear injury	Don’t fly until a doctor has assessed you

For trip planning, the simplest version is this: make your last deep session at least 24 hours before your flight, and spend the final day snorkelling, resting or exploring on land.

Driving up to the hills counts too

Altitude is altitude, whether you reach it by plane or by road. Several South Indian hill stations sit at similar or higher altitudes than a pressurised airliner cabin: Ooty and Kodaikanal are both above 2,000 metres, and Munnar is well over 1,000 metres. Diving off Pondicherry and then driving up to Kodaikanal, or finishing at Netrani and heading into the coffee hills around Chikmagalur, deserves the same thinking as a flight.

The same conservative wait applies. If you’re planning a combined coast-and-hills holiday, do the hills first and the diving second.

Ears, sinuses and the flight home

Flying puts your ears and sinuses through pressure changes, mostly as the plane descends. If you’ve had any ear or sinus trouble on the trip, that matters. A middle ear that’s already irritated from diving can get worse with cabin pressure changes, and a blocked nose makes equalising on the descent harder.

• Equalise early and gently as the plane starts to descend, by swallowing, yawning or a gentle Frenzel or Valsalva. Never force it.
• Avoid flying with a heavy cold if you can. Our post on freediving with a cold explains why congestion causes problems in both directions.
• If you have ear pain, reduced hearing, ringing or dizziness after diving, see an ENT before you fly where possible. Ear care for freedivers covers the warning signs.
• After a suspected lung squeeze, ask a doctor before flying.

Symptoms that mean you shouldn’t board

Decompression sickness after freediving is uncommon, but it’s easy to dismiss as tiredness or heat. Don’t fly, and get medical help, if you notice any of these after diving:

• unusual tiredness or feeling generally unwell
• dizziness or vertigo
• numbness, tingling or weakness anywhere, especially on one side
• problems with vision, speech or balance
• confusion, or a change in behaviour that others notice
• a headache that’s unusual for you
• joint pain, or an itchy, blotchy rash
• shortness of breath, chest pain or coughing blood

Give first aid oxygen if it’s available and someone is trained to use it, and call your dive insurer’s emergency line if you have one. Organisations such as DAN run emergency hotlines for diving injuries, so save the relevant number in your phone before the trip.

Safety: If you have any symptom that could be decompression sickness, don’t fly, even if you start to feel better. Get medical advice first, because the lower cabin pressure can make DCS worse.

Planning the end of an Andaman or Lakshadweep trip

Island trips make this easy to get wrong. A typical Andaman itinerary ends with a ferry from Swaraj Dweep (Havelock) back to Port Blair and a flight out soon after, so it’s tempting to squeeze in one more deep session on the last morning. Don’t. Book your last depth day at least a day before the flight, and keep the final day for shallow reef snorkelling or the beach. Lakshadweep is similar: flight options are limited, and it’s easy to plan diving right up to departure.

Our guide to freediving in the Andaman Islands has more on ferries and timing, and planning a freediving trip from India covers insurance and bookings. Stay tuned for the freediving.in community, launching soon.