Snorkeling in Thailand is easy to do and easy to underestimate: the main risk is drowning, not sharks or jellyfish. Wear a life jacket or buoyancy vest even if you swim well, stay close to the boat and other people, tell the crew about any heart or breathing condition, and get out of the water the moment you feel unwell.
Most visitors snorkel from a day-trip boat: a speedboat or longtail that stops at three or four reefs around Phi Phi, the Similan or Surin islands, Ang Thong or Koh Lipe, and gives you a set time in the water at each. The Divers Alert Network (DAN), a diving-medicine organization, puts the problem plainly: snorkeling is seen as harmless, so most snorkelers get no proper training, and resort programs offer little instruction or emergency preparation.
This page is about snorkeling from a boat. For swimming off the sand, see our page on beach flags and rip currents; the boat ride itself is described in our page on what a speedboat trip is really like.
Snorkeling from Thai boats: the essentials (October 2026)
- Main risk
- Drowning, often after a cardiac event, panic, a current or a boat strike (DAN)
- Higher-risk groups
- Older snorkelers and people with high blood pressure or heart disease (DAN)
- Life jackets
- Marine Department requires them on passenger boats; it campaigns for passengers to wear them
- Coral
- Never stand on or touch it; keep at least 2 m away in marine national parks (DNP)
- Emergency
- 1669 ambulance, 191 police
Why a life jacket makes sense for strong swimmers too
A life jacket feels like something for children and non-swimmers. On a snorkel trip it is closer to a seat belt. DAN lists what can lead to drowning in snorkelers: sudden cardiac arrest, fluid in the lungs triggered by immersion (immersion pulmonary edema), blacking out after holding your breath, inhaling water, being hit by a boat, and strong tides or currents. Swimming skill helps with only some of those. A vest keeps your face up if you feel faint, lets you rest without standing on coral, and makes you easier to see.
Thai rules put life jackets on the boat, not necessarily on you. The Marine Department requires passenger boats to carry life jackets, buoyant cushions and lifebuoys ready for use, and it campaigns for passengers to wear them; we could not confirm a legal duty for snorkelers to wear one in the water. Many boats hand out orange jackets or foam vests at the ladder. Take one, fasten every strap, and if it is too big, ask for a smaller size.
Non-swimmers can snorkel, with a jacket and a rope. Ask the crew for a life jacket that fits, stay within reach of the boat's float line or a ring, and snorkel next to someone who swims well. Floating face-down with a jacket on is enough to see the reef.
Currents around the islands, and why the boat does not wait
The water between islands moves. Tidal flows run through channels and around headlands, and a current that is barely noticeable when you jump in can carry you a long way in 20 minutes. DAN warns that currents can sweep snorkelers out to sea or onto rocks, and that novice snorkelers should not swim in remote and unpopulated areas.
- Start against the current. Swim up-current first, so the drift brings you back towards the boat when you are tired.
- Look up every minute or two. Check where the boat is. People lose the boat because they follow a fish.
- Know the signal and the time. Ask how the crew calls people back (a whistle, a horn, a wave) and when the boat leaves.
- If you are drifting, do not fight it. Lift an arm and wave, float on your back, and let the crew come to you.
Busy day-trip boats run on a tight schedule between several stops. Crews count heads, but they are counting dozens of people in matching vests. Make sure the crew knows you are in the water, and stay with the group.
Heart problems, panic and older snorkelers
DAN says cardiac arrest and immersion pulmonary edema are more likely in older people and in people with pre-existing conditions, especially high blood pressure and heart disease. Exertion, a long swim back against a current, a big lunch and the stress of a crowded ladder all add up. If you have a heart or lung condition, talk to your doctor at home before the trip about whether snorkeling suits you.
Panic is the other common thread. It often starts with something small: water in the snorkel, a mask that floods, a wave over the head. Breathing speeds up, the snorkel feels like it is not giving enough air, and people pull off their mask and try to stand, sometimes on coral. The answer is to stop, lift your head, take the snorkel out, breathe, and hold on to your vest or the boat's line until you are calm.
Get out and get help if you feel chest pain, sudden breathlessness or confusion in the water. Wave to the crew at once. Anyone who inhaled water and keeps coughing or feels short of breath afterwards, or who was pulled out unconscious, should be seen by a doctor the same day, even if they feel better; call 1669 for an ambulance.
Mask fog, water in the snorkel and other small problems
Most bad snorkeling experiences are equipment problems that turn into panic. A few habits help:
- Test the mask on the boat. Put it on without the strap, breathe in through your nose, and it should stay on your face. Hair under the seal and a moustache let water in.
- Stop fog before you go in. Rinse the mask in sea water before each stop; some boats keep a bucket for it. A brand-new mask may need cleaning before it stops fogging.
- Clear the snorkel with a sharp breath out, then breathe in slowly in case some water is left.
- Do not over-breathe before a dive under. DAN advises against hyperventilating before breath-hold dives, and suggests one or at most two deep breaths, because it raises the risk of blacking out underwater.
- Be careful with full-face masks. DAN has received incident reports linked to full-face snorkel masks and is studying whether they raise the risk; until there is a result, nobody can say they are safer for beginners.
Fins that fit make a big difference against a current, so try them on before the first stop. If you get seasick on the boat, our guide to motion sickness on speedboats and minivans explains what to buy before the trip.
Boat traffic, coral and the park rules
DAN says being struck by a boat is "not uncommon" among snorkelers, and advises staying within marked areas and watching for traffic. At popular reefs several boats anchor at once, and longtails and speedboats move between them. Stay between your boat and the reef, not out in the channel, and wear a brightly colored vest or rash guard so drivers can see you.
Many of the best reefs are inside marine national parks. The Department of National Parks asks visitors not to touch, step on or handle coral and to keep at least 2 meters from reefs, and the parks ban sunscreens with certain coral-harming ingredients; our page on the sunscreen ban in marine parks lists them. Standing on coral also hurts you: it cuts feet, and stonefish and sea urchins hide in exactly those shallow spots, as our stonefish warning from Koh Lipe shows. A long-sleeved rash guard helps against sunburn and, in the rainy months, jellyfish; our guide to box jellyfish in Thailand covers the season and the vinegar first aid.
What to tell the crew, and where to go
Before the first stop, tell the crew or guide three things: whether you can swim, any heart, breathing or epilepsy condition, and whether you have snorkeled before. It changes where they put you and how closely they watch. Ask whether they carry a first-aid kit and oxygen, and how they would get a sick passenger to land.
Snorkel trips in Thailand run from many bases. Koh Lipe has reef within reach of the beach and a short longtail ride to Koh Adang and Koh Rawi, described in our guide to snorkeling and diving around Koh Lipe. The Similan Islands and Surin Islands are open-water trips far from shore, so the advice above about currents and boats matters more there. If you move on from snorkeling to scuba, our page on dive safety and recompression chambers takes over.
Thailand's Department of Disease Control counted 36,870 drowning deaths in the ten years 2015 to 2024, an average of more than ten a day. The figure is not split by activity, so it does not tell you how many were snorkelers, but it is a reminder that water accidents are common. Save the emergency numbers for Thailand before the trip.
Frequently asked questions
Can you snorkel in Thailand if you cannot swim?
Yes, many non-swimmers do, but only with a properly fitted life jacket, close to the boat and next to someone who swims well. Tell the crew you cannot swim before the first stop, and stay in sheltered, shallow areas away from boat traffic.
Do I have to wear a life jacket when snorkeling in Thailand?
We could not confirm a legal duty to wear one in the water. Thai boat rules make operators keep jackets on board, and the Marine Department urges passengers to put them on. DAN names drowning as the main snorkeling risk, so wearing a vest is sensible even for good swimmers.
Is snorkeling dangerous for older people?
Not for most, but DAN says cardiac arrest and immersion pulmonary edema are more likely in older snorkelers and people with high blood pressure or heart disease. Ask your doctor before the trip if you have a heart condition, and get out at the first sign of chest pain or breathlessness.
Are full-face snorkel masks safe?
Nobody can say for certain yet. DAN has received incident reports involving full-face masks and is studying whether they increase risk. A standard mask and snorkel is the tested choice, and the one boat crews know how to help with.
Sources
- Divers Alert Network – Travelers Medical Guide: snorkeling and scuba diving (2022) (checked October 2026)
- Divers Alert Network – Full-face snorkel mask safety study (checked October 2026)
- Department of Disease Control – Drowning deaths 2015–2024 (5 November 2025) (checked October 2026)
- Thansettakij – Marine Department water-safety measures (23 November 2025) (checked October 2026)
- Khaosod English – DNP marine-park rules on sunscreen and coral (17 October 2025) (checked October 2026)
- UK Foreign, Commonwealth and Development Office – Thailand: safety and security (checked October 2026)