Koh Tao

Diving is the reason most people come to Koh Tao, and the island is purpose-built for it. Dozens of dive schools cluster along Sairee and Mae Haad, offering everything from a half-day 'try dive' to the four-day Open Water course and on to Divemaster training, generally at some of the lowest prices anywhere. The dive sites are close and varied: Chumphon Pinnacle, a granite seamount famous for schooling fish and occasional whale sharks; Sail Rock, out toward Koh Phangan, with its dramatic vertical chimney swim-through; Southwest Pinnacle; and the HTMS Sattakut, a former navy vessel sunk as an artificial reef and now a popular wreck dive. Warm water, gentle conditions and shallow reefs make it ideal for beginners, while the pinnacles keep experienced divers happy. Book with a school that keeps small groups and check its safety record rather than chasing the rock-bottom price. Non-divers can join many boats to snorkel the same sites.

Koh Nang Yuan is the postcard that sells Koh Tao: three little granite islands joined by a shimmering triple sandbar, just off the northwest coast. It is privately managed, with an entrance fee, and single-use plastic bottles are banned to protect the setting, so bring a refillable one. The classic move is to climb the short but steep path to the viewpoint on the largest islet, where a boulder-framed lookout takes in the whole sandbar and the impossibly clear water below. Down at sea level, the snorkelling straight off the beach is among the best on the island, with coral gardens and reef fish in easy, shallow reach. It gets busy when the day-trip boats arrive mid-morning, so come early or late to have the sandbar to yourself. You reach it by a ten-minute longtail or taxi-boat from Sairee. Wear reef shoes for the rocks and go easy on the fragile coral.

John-Suwan, sometimes written Jon-Suwan, is the finest viewpoint on Koh Tao, and arguably one of the best in the Gulf. A short but genuinely steep scramble up a rocky trail at the island's southern end brings you to a bare granite outcrop with views in two directions: on one side the twin bays of Chalok Baan Kao and Thian Og curl below you, and on the other the open sea stretches away. The rock can be slick, so wear proper shoes and take care near the edges, especially with children. A small access fee is usually collected at the trailhead. It is a quick climb, twenty minutes or so each way, which makes it easy to fit around a beach afternoon. Go for sunrise or late afternoon to avoid the midday heat on the exposed rock, and carry water. The view over the two horseshoe bays is the shot that ends up on everyone's camera roll.

Despite the name, Shark Bay is one of the gentlest and most rewarding snorkelling spots on the island, and the 'sharks' are the reason to go. This is Thian Og bay on the south coast, where small, harmless blacktip reef sharks patrol the shallows, along with a healthy population of green sea turtles that give the island its name. Swim out from the beach over the seagrass and coral and there is a real chance of gliding above a turtle grazing below, or spotting a reef shark cruising the edge of the reef, neither of which poses any danger to snorkellers. Mornings tend to be calmer and clearer. You can reach the bay by boat, by scrambling over from Chalok Baan Kao, or through the resort that sits above it, where a small access fee may apply. Bring your own mask and fins if you can, and keep a respectful distance from the turtles rather than chasing them.

Sairee is Koh Tao's main beach and the beating heart of island life, a gentle arc of pale sand running for well over a kilometre down the west coast. Behind it lies a dense ribbon of dive schools, guesthouses, cafes, bars and shops, all packed into a walkable, mostly car-free village lane. The swimming is calm and shallow, fine for a cooling dip between dives, though the beach is more about atmosphere than seclusion. Its real magic is sunset: facing due west, Sairee delivers the island's best evening skies, and the beachfront bars fill up with divers swapping stories over a drink as the sun drops. Fire shows and live music carry the night along the southern end. By day it is the practical base for booking trips, renting gear and eating well. If you want quiet you will look elsewhere, but for convenience and buzz nothing on the island beats it.

Freedom Beach is the pretty, low-key counterpoint to busy Sairee, tucked into the south of the island beyond Chalok Baan Kao. A short walk, boat ride or scramble past Haad Tien brings you to a small, soft crescent of sand with clear, calm water and a coral reef just offshore that makes for easy swimming and good snorkelling. It is more relaxed and far less developed than the main strip, with a beach bar or two and shady trees to laze under. Crucially, it sits right at the foot of the trail up to the John-Suwan viewpoint, so the classic plan is to snorkel and swim here, then climb up for the panorama. A small access fee is sometimes charged through the resort that manages the approach. Bring water and snacks, since options on the sand are limited. It is the sort of place you come to do very little, very happily, for an afternoon.