Freediving in Thailand: Courses on Koh Tao, Costs and the Blackout Rule

Freediving is diving on a single breath, with no tank: you take one slow inhale at the surface, follow a line down into blue water, and come back up on that same breath. In Thailand that usually means a two to three day course on Koh Tao, in water warm enough that your body relaxes almost before your mind does. I came to it late, after years as a divemaster, and it taught me more about my own nerves than anything I did with a tank on my back. Here is how a first course works, roughly what it costs, and the one rule that matters more than every other.

What freediving actually involves

Recreational freediving means diving down a weighted line from a surface buoy on one held breath, usually to somewhere between 10 and 20 metres on a first course. The kit is simple: a low-volume mask, long fins, a snorkel, a thin wetsuit and a weight belt. No regulator, no tank, no gauges to read. What you are actually learning is control: slow breathing before the dive, a relaxed descent, and equalising your ears as the pressure builds.

The physics are blunt. At 10 metres the pressure is double what it is at the surface, so the air in your lungs is squeezed to about half its volume, and it keeps shrinking as you go deeper ¹. That is why equalising early and often matters so much, and why your instructor will stop you the moment a dive starts to feel like a fight. The sport’s international standards body, AIDA, builds its whole training system around that progression, depth earned slowly and never forced ².

Why Koh Tao is the place to learn

Koh Tao is Thailand’s main freediving centre because deep, calm water sits a short boat ride from shore and the island already runs on dive training. The water is roughly 28 to 30°C for most of the year, which matters more for freediving than for scuba: cold makes you tense, tension burns oxygen, and a warm body simply holds its breath longer ³.

The island’s sheltered bays give you a line in 20 metres or more of water within minutes of the beach, and the density of schools means instructors who teach this every day. If you have already done your scuba course there, you will know the rhythm of the place; how that works is covered in learning to dive on Koh Tao. Freediving schools also operate on Koh Phangan, Koh Lanta and around Phuket, but Koh Tao has the deepest bench of them.

How a first course runs

An entry freediving course takes about two to three days and splits into theory, a pool or shallow session, and open-water dives on a line. Theory covers how your body responds to a breath-hold, why hyperventilating before a dive is dangerous, and how to rescue a buddy who blacks out. The pool or shallow session works on static breath-holds (floating face down, timing how long you can comfortably stay) and dynamic swims underwater.

Then you go to sea for dives on the line. By the end of the course, AIDA’s main beginner certification, AIDA2, for example, is a course of at least three days that asks a student to show a two-minute static breath-hold and a 40 metre underwater swim in the pool and a 12 metre dive down the line, alongside rescue drills ². Other agencies set similar targets. Most people are surprised: the two-minute hold that sounds impossible on day one usually arrives by day two, once you stop fighting the urge to breathe and learn to let it pass.

On cost, a first course on Koh Tao runs roughly 5,500 to 7,500 baht as an approximate starting point, usually including tuition, kit hire and certification. That is well below an Open Water scuba course. Prices change constantly, so confirm the current price, the maximum students per instructor (two or three per instructor in the water is good), and how many open-water sessions are included before you pay.

Blackout: the risk you cannot feel coming

The serious danger in freediving is blackout, a loss of consciousness from low oxygen that usually happens near or at the surface and can come with no warning at all. On the way up, the falling water pressure lowers the oxygen pressure in your lungs and blood, and the last few metres and the first breaths at the surface are where it tends to bite. The diver often feels fine until the moment they do not ¹.

That is why the rule is absolute: never freedive alone. Freedivers work one up, one down: while you dive, a trained buddy waits at the surface, watches you all the way back, and stays with you for at least the first 30 seconds after you breathe. If you black out, they keep your airway out of the water, take off your mask, and talk and blow you back to breathing. Most surface blackouts end in a frightened diver coughing on the buoy, not a tragedy, but only because someone was watching.

Two more points from the course are worth repeating. Hyperventilating before a dive does not add oxygen; it lowers carbon dioxide, delays the urge to breathe, and makes blackout more likely. And the snorkellers you see diving down repeatedly on the reef, alone and holding their breath as long as they can, are taking exactly the risk that freediving courses exist to remove. My own lesson came on the second day of my course: I surfaced from a 15 metre dive feeling perfectly normal, and my instructor told me afterwards that my lips had gone blue for a second and my hand had twitched on the buoy. I had felt nothing. I have never been in the water on a breath-hold without a buddy since.

Ears, sun, boats and stings

After blackout, the most common freediving problems in Thailand are ear injuries, sun, boat traffic and marine stings, and all four are preventable. Ear squeeze from forcing a descent past a blocked ear is the injury instructors see most; many beginners find the standard Valsalva technique stalls somewhere past 10 metres and learn the Frenzel technique to go further. Never push past pain, and turn the dive at the first doubt ¹.

Freediving is long hours lying face down on the surface, so cover your back and legs with a rash vest or wetsuit; sunburn on a two-hour session is otherwise guaranteed. Always dive from a clearly marked buoy with a dive flag, because longtail boats move fast in busy bays and a head in the water is hard to see. In the Gulf’s wetter months, jellyfish can be a concern on some beaches, and the first aid is set out in the jellyfish and marine stings guide.

If something does go wrong, call 1669 for the national ambulance ⁴, and know where the nearest decompression chamber is: Thailand has them only on Koh Tao, Koh Samui and Phuket ¹. Breath-hold divers do get pressure injuries, especially on deep, repeated dives, so the chamber question is not just for scuba divers.

Insurance and mixing freediving with scuba

Many standard travel policies exclude freediving outright or cap breath-hold diving at a shallow depth, so check the wording before your first session. Policies that cover recreational scuba do not automatically cover freediving, and some name a maximum depth that a course will take you past ⁵. Diving-specific cover such as Divers Alert Network membership is one option, as long as you confirm it names freediving ⁶. The exclusions that most often catch people out are detailed in the travel insurance for adventure guide.

If you are combining both on one trip, DAN’s general guidance is to avoid freediving after scuba diving on the same day, because breath-hold descents can add to the nitrogen already in your body from a tank dive ¹. The easy fix on Koh Tao is to freedive in the morning or on a separate day.

When to go and where to freedive

Koh Tao and the Gulf islands can be freedived most of the year, with the poorest conditions around October to December; the Andaman side is best from roughly mid-October to mid-May. That is the same two-coast rule that shapes all Thai diving, set out in the diving in Thailand guide ³.

For a first course, Koh Tao between January and September is the safe bet: calm water, good visibility and plenty of schools running daily. Once certified, Koh Lanta and the islands off Phuket give you Andaman blue water in the dry season. Start shallow, dive with people better than you, and let depth come on its own schedule. The best freedivers I met on Koh Tao were never the ones pushing hardest; they were the ones who looked half asleep on the buoy.

---

General information, not freediving instruction. Conditions, prices and school standards change; always freedive within your training, never alone, follow your instructor, and confirm your insurance covers breath-hold diving.