Koh Samui sits in the Gulf of Thailand surrounded by archipelagos with rich marine life. For divers, it serves as an excellent gateway to some of the region's best underwater sites and a quick ferry connection to world-famous Ko Tao.

Best Dive Sites Near Samui

Sail Rock (Hin Bai)

The premier dive site in the Gulf of Thailand. An underwater pinnacle rising from 40 m to the surface, with vertical walls covered in corals and abundant fish life. Whale sharks are regularly spotted here from November to March. Journey time from Samui: 1.5-2 hours by speedboat. Recommended for Open Water certified divers and above.

Ko Tao

An island 60 km north of Samui and one of the world's top dive training destinations. Over 50 dive centres, visibility up to 30 m in the dry season, and more than 20 official sites. Beginners enjoy Mango Bay, Japanese Garden and Shark Island. Accessible by ferry in approximately 2 hours.

Chumphon Pinnacle

One of the most celebrated sites in the Gulf, at 14-36 m depth. Granite pinnacles carpeted with coral, large schools of fish, occasional whale sharks. Reach time: 2-3 hours from Samui.

Ko Madsum and Ko Tean

Small islands south-west of Samui with shallow reefs to 15 m depth, ideal for beginners and snorkellers. Coral gardens are notably well-preserved. Daily trips depart from Ban Tai pier.

PADI Certification on Samui

Several PADI-accredited centres operate on the island. The Open Water Diver course takes 3-4 days: theory (available in advance via PADI eLearning), pool skills sessions and 4 open-water dives. Full course cost: 10,000-14,000 THB including equipment and transfers. Advanced Open Water, Rescue Diver and speciality courses are also widely available.

Try Diving Without a Certificate

If you have never scuba dived and do not want a full course, Discovery Scuba Diving lets you experience one supervised dive at 3-5 m depth with no prior training. Duration: 1-2 hours. Cost: 1,500-2,500 THB. Minimum age: 8 years. The instructor stays beside you throughout.

Diving Season

Best conditions run February-October. The north-east monsoon (November-December) reduces visibility and makes some sites inaccessible. Whale shark encounters at Sail Rock peak October-December and March-April.

Safety and After Your Dive

Observe the 18/24-hour no-fly rule after diving. Bangkok Hospital Samui maintains a decompression chamber. Always carry your certification card — operators must verify it before boarding. A 3 mm wetsuit is comfortable in 28-30 degree water, though cooler at depth.

Night Diving

Night diving reveals a different reef: lobsters, crabs, octopus and open coral polyps emerge after dark. Most dive centres on Samui offer night trips to nearby reefs. Minimum level: Open Water; recommended experience: 10+ daytime dives. Cost: 2,500–3,500 THB for two dives including torch hire. The PADI Night Diver speciality is available in one day and develops navigation and buoyancy skills essential for low-visibility conditions.