Emergency numbers: 1669 for an ambulance, 1155 for the Tourist Police (English spoken), 191 for the police.
In the sea
- Surf. From October to December the east-coast beaches take the brunt of the monsoon swell. Red flags mean no swimming.
- Box jellyfish. Six of the seven deaths from box jellyfish in Thailand recorded between 1999 and 2015 happened on Samui and Koh Phangan. They are seen mainly from July to December. Swim inside nets where they exist.
- If stung: get out of the water, pour vinegar over the area for at least 30 seconds, remove tentacles carefully, and call 1669. Do not rub with sand or rinse with fresh water. Vinegar posts have been placed on some beaches, but they are not always stocked.
- Boats and jet skis come close to the shore on busy beaches. Swim inside marked areas.
On the roads
- Most accidents involving tourists are on motorbikes. Wear a helmet, avoid riding after rain on the hill roads, and never ride after drinking.
- Rental motorbikes are often uninsured, whatever the shop says. Read the agreement, photograph the bike, and do not leave your passport as a deposit if you can avoid it. In a dispute, the Tourist Police can help.
- All-terrain vehicles are generally not registered for road use.
Waterfalls and hills
Rocks at Na Muang and other waterfalls are slippery, and people have died in falls. Stay on paths and do not climb cascades, especially after rain.
Health
- Tap water is not drinkable. Ice in restaurants is made from purified water.
- Dengue fever is carried by mosquitoes on the island; use repellent, day and evening.
- There are several private hospitals, among them Bangkok Hospital Samui and Samui International Hospital, and a government hospital in Nathon.
Animals
Elephant camps on Samui are not regulated, and riding still takes place despite the risks to people and animals. Monkey shows use captured macaques. If you want to see animals, choose places that do not offer riding or performances.