Meet Nok: A Koh Tao Dive Instructor on Coral, Whale Sharks, and What Tourists Do That Makes Her Cringe
Nok Srisomboon has been a dive instructor on Koh Tao for nine years. She's logged over 5,000 dives, trained hundreds of new divers, and spent more time underwater around this island than most fish. She grew up in Surat Thani on the mainland, came to Koh Tao at 22 for a PADI course, and never left.
Catch her at a cafe in Mae Haad at 7 AM — early, because her first dive group launches at 8:30. Rash guard on, pad krapao over rice in front of her, weather app open and studied with the intensity of a pilot.
How did you end up staying on Koh Tao?
Open Water in 2017 — four days, 8,500 baht. On the third dive, at Japanese Gardens (a shallow, forgiving site), a seahorse sat on a piece of coral, holding on with its tail, completely calm. The instructor pointed it out, and that was the end of any other plan.
Two weeks back home in Surat Thani, then back to Koh Tao for good — Advanced, Rescue, Divemaster, Instructor. Now she teaches. That seahorse's descendants are still at Japanese Gardens, and she still checks on them.
Which dive shop should someone choose? There are seventy on the island.
Fifty are good. Ten are excellent. Ten are worth avoiding.
What to look for: instructor-to-student ratio (4:1 maximum for Open Water, never higher), whether the shop owns its own boat or shares one, how it handles equipment maintenance, and — this is the one people skip — whether it takes part in coral conservation.
Ask to see the training pool and the boats. Neglected boats usually mean neglected safety gear. And read recent reviews — not the ones from 2020, the ones from last month.
Nok won't name the shops she dislikes. She will say the cheapest option is usually cheap for a reason.
Best dive site on Koh Tao?
Sail Rock, and it isn't close. A granite pinnacle rising out of the deep, plastered with life — enormous schools of batfish, barracuda, chevron, sometimes bull sharks. The chimney, a vertical swim-through from 18 meters to 5 meters, is one of the most thrilling things you can do underwater.
And in March and April, the whale sharks arrive. Nok has seen them at Sail Rock seven times in nine years, and every time lands like the first. Your brain genuinely can't process the size. You spot a shadow, you think manta ray, and then it keeps getting bigger and bigger until it's a whale shark and you forget to breathe — which, underwater, is a problem.
What do tourists do that makes you cringe?
Standing on coral. STANDING ON CORAL.
(She puts down her fork.)
Coral is an animal. It grows about one centimeter a year. Stand on a coral head for a photo, or because you're tired, or because your buoyancy is off, and you can erase decades of growth in one second. One second.
The rule every Open Water student here gets: if you can't hold your buoyancy, go up. Never sink down onto the reef. Surfacing beats touching the coral, every time. Some instructors don't hammer this hard enough, and that's what makes her angry.
Chemical sunscreen too. The oxybenzone and octinoxate in most bottles bleach coral on contact. Use mineral sunscreen — zinc oxide-based. It costs more and leaves a white film on your skin. The reef outranks your tan.
How are the reefs doing?
Mixed. Some sites are thriving — Japanese Gardens, Twins, and the deeper reaches of Sail Rock hold healthy coral coverage. Others, especially the shallow ones near Sairee where the snorkelers gather, have taken damage from tourism, anchoring, and the 2010 and 2016 bleaching events.
The good news: Koh Tao runs the most active coral restoration program of any island in Thailand. Multiple dive shops grow coral fragments on underwater frames and transplant them onto damaged reefs. New Heaven Reef Conservation Program at Chalok Baan Kao leads the effort, with thousands of fragments planted — and you can volunteer for a day.
The bad news: rising water temperatures are the biggest threat, and no amount of local conservation fixes that.
Freediving has gotten big here. Thoughts?
It's a joy to watch. Ten years ago, freediving on Koh Tao meant maybe five people. Now there are multiple schools, international competitions, and freedivers from all over the world training in the bay.
The water does the rest — warm, calm, clear. Apnea Total and Blue Immersion are both excellent schools. A Level 1 course runs about 7,000–9,000 THB for two days. Hold your breath for 30 seconds today and you'll be doing 2–3 minutes by the end.
What Nok loves is the silence. Scuba is noisy — the regulator, the bubbles. Freediving is just… water. And the marine life reads it differently: fish don't dart away, they come closer.
Best non-diving experience on Koh Tao?
John-Suwan Viewpoint at sunset. A 30-minute hike from Chalok — steep, sweaty, entirely worth it. At the top, Shark Bay sits on one side and the open ocean on the other. Bring a beer. Watch the sky turn colors.
And Tanote Bay for snorkeling: walk in from the beach, swim out 20 meters, and you're in a coral garden of clownfish, trigger fish, and sometimes a resident turtle. No dive certification needed. No boat needed. Just a mask and some reef-safe sunscreen.
What do you wish tourists knew?
The ocean here is alive. Every piece of coral is an animal. Every fish holds a territory. The reef is a community as intricate as a city — when you dive or snorkel, you're a guest in someone's home.
So treat it that way. Don't touch. Don't take. Don't stand on the furniture.
And tip your dive instructor. They work long hours in the sun for modest pay because they love the ocean; a 200-baht tip after a course costs you six dollars and means a great deal.
Will you ever leave Koh Tao?
(Long pause.)
She goes home to Surat Thani for Songkran and New Year. Her mother asks when she'll get a real job. Nok's answer never changes: she has one — she shows people the most beautiful thing on the planet.
Her mother still doesn't quite understand. But she stopped asking last year. So… progress.
Nok dives daily out of Mae Haad. If you're chaining Thai islands afterward, Koh Chang near the Cambodian border trades dive boats for jungle waterfalls and far fewer crowds.
And for more of the same world-class, budget-friendly diving abroad, Nusa Lembongan off Bali delivers manta rays and mola mola from a similarly tiny island base.
