Diving in Koh Samui
Gateway to the Gulf of Thailand
One of Thailand's best loved islands, Samui's charms are evident as soon as you arrive at its award-winning thatch-roofed airport.
When you stay on the island of Koh Samui you will not only enjoy the excellent beaches and wonderful nightlife, but you will also have access to the best scuba diving in this part of Thailand. The sites around Koh Tao can also be dived via daytrips from Samui.
The dive sites of Koh Samui include the famous Sail Rock and are characterised by submerged pinnacles, large rocky seamounts, colourful corals and reefs with plenty of marine life for you to enjoy, including good chances to see whale sharks. Because the Gulf of Thailand is a large sheltered bay, the seas tend to be calm and provide excellent conditions for diving throughout the year.
With some excellent hotels and resorts, great beaches, the spectacular Ang Thong National Marine Park, and a mix of nightlife and quiet retreats, Samui Island caters to all sorts of tourists including young independent travellers, families and couples seeking a romantic beach break. When Phuket and the west coast are in low season, many consider that Koh Samui is the perfect destination for sun, sand, sea and diving.
Dive Site Descriptions
Sail Rock - This is a 30m tall granite pinnacle half way between Koh Phangan and Koh Samui and is generally thought of as the best dive site in the Gulf of Thailand. There are no other rocks nearby so it acts as a congregation point for all fishes in the surrounding area. It is a real highlight because whale sharks are commonly sighted here. Whether you are on the surface or below, you will be amazed at how long these sharks stay around seemingly enjoying the presence of divers.
On a sunny day when the light filters down into the aquamarine waters, the granite boulder looks spectacular. Schools of trevallies roam all over Sail Rock and energetically hunt the smaller fish that bunch together for protection from these darting raids. There are several more rocks a little deeper that can be seen from the main pinnacle and these are home to reef sharks.
In terms of topography, 'The Chimney' will probably stay long in your memory. You can enter the rock through a hole at around 20 metres and exit either at 15 metres or 10 metres having checked out the masses of glassfish, boxer shrimps, moray eels and other inhabitants of the chimney which makes a lovely swim-through.
Koh Yippon - This is one of Samui's most popular dive sites and found in a sheltered location in the north of the Angthong Marine Park. With a maximum depth of 18m, this mostly shallow site is great for both scuba divers and snorkelers with plenty of soft corals, barrel sponges and anemones easily visible from the surface. In deeper sections you can spot large snappers, blue-spotted sting rays and schools of fusiliers and yellow-tailed barracuda.
Koh Wao (a.k.a Dragon Island) - Resembling a sleeping dragon, this island features a shallow bay full of submerged boulders and teems with marine life. The water here is usually calm with currents absent or mild so it is a dive site suitable for all levels. There is a healthy number of hard coral species and anemones. Check in and around the sandy floor at the base of the boulders at a maximum of around 20m for sting rays. Schools of fish commonly sighted include snappers and fusiliers, as well as barracuda and trevallies.
How to Dive Samui
The dive sites can be visited by daytrip boats from Samui Island. Dive boats depart every morning, normally in quite small groups. You will normally return at 5:00 pm in time to return to your resort and relax for the evening. You can book daytrips only, or combine your diving trips with accommodation in one of our recommended Koh Samui resorts.
Got a question?
Have a look through our Frequently asked questions
The dive sites in the Gulf of Thailand can be visited throughout the year. However the peak season, which sees the optimum conditions, runs from March to September, with underwater visibility reaching up to 30-35m at its best. There may be a reduction in visibility during the October to November period when monsoon winds and swells can be present. However these are rarely sufficient to interfere with diving trips, except for maybe making boat journeys a little bumpier.
If you are planning a dive trip between November and February, Koh Samui is not the best bet since rain and wind, brought by the northeast monsoon, can visit the Gulf, causing waves and a drop in visibility to 10m.
Water temperature ranges between 27°C and 30°C, with the coolest water in the months of October and December. The coolest time of the year however, is also the best chance to see sharks in the area as they prefer colder waters.
Whale sharks mainly visit the area in March and April, and again in September and October.
Good for: Small animals, beginner divers, dive value-for-money, snorkelling and non-diving activities
Not so good for: Wrecks and drift dives
Depth: 5 - 40m
Visibility: 5 - 25m
Currents: Can be strong
Surface conditions: Calm to choppy
Water temperature: 27 - 30°C
Experience level: Beginner - advanced
Number of dive sites: ~6, but >20 including Koh Tao
Access: Day trips
Recommended length of stay: 5 days
• Koh Samui travel information
View a map of:
• Samui Island - Thailand