'Turtle Island' (as the name 'Koh Tao' means in English) has long been a magnet for backpackers and traveller types who want learn about scuba diving. The many shallow bays are used to certify more PADI student divers than anywhere else in the world outside of Australia.
The island, located to the north of Koh Samui and Koh Phangan in the Gulf of Thailand, offers highly affordable day trips to many easy dive sites dotted around its coastline.
There are also a couple of offshore pinnacles - Chumphon and South West Pinnacle - which offer more challenging dives and the opportunity to encounter bigger fish, as well as diving with whale sharks in season. Chumphon Pinnacle in particular has gained a favourable reputation as being one of the best dive sites in the Gulf of Thailand.
Ao Leuk - This shallow bay's easy, relaxing diving is strongly recommend for beginners or for divers that haven't got wet for a while. The Thai name means 'Deep Bay' which is something of a misnomer since it is one of the shallowest of Koh Tao's dive sites, with its sandy bottom allowing a maximum depth of only 12-14 metres. There are a surprising amount of reef fish such as butterflyfish and angelfish, schools of juvenile yellowtail barracuda and turtles.
Chumphon Pinnacle is Koh Tao's best and most famous dive site and should definitely be part of your east coast Thailand diving itinerary. It's a granite pinnacle to the north west of the island and which starts 12 metres under the surface and goes down to a maximum depth of 35 metres. There is one main pinnacle which is surrounded by a dozen or so smaller rocks in the deeper areas. Show more
The base of the main rock is completely covered in anemones which gently sway back and forth in the current. They are full of anemonefish of several varieties including the western clownfish, or 'Nemo's. This is a good site to see big fish including grouper, batfish, yellowtail barracuda and many others.
Huge schools of jacks can make it difficult to even see the pinnacle as they rush around divers. Whale sharks are a common visitor here, the best time being from February to April, and even whales have been spotted. Leopard sharks are often seen resting on the sandy bottom at the reef edge. Other species here include lionfish, fusiliers, rabbitfish and schooling bannerfish.
The depth and currents mean that this is not a site for complete beginners. It's a good idea to have some deep scuba diving training before you visit Koh Tao; at the least you should be PADI Advanced Open Water certified.
Hin Wong Pinnacle - This is certainly a unique dive at Koh Tao Island. The large granite pinnacle is at the northern end of Hin Wong Bay. The north side is beautiful with purple soft corals and many different kinds of sea fans, whip corals and black corals. Blue and black damsels swarm around you as if in greeting as you enter the water. Down on the bottom you might see small groups of shrimpfish driftby. Show more
As you spiral up the rocks to the shallower section you'll find groves of Christmas tree worms embedded in the hard coral reef. There are white-eyed moray eels hiding in the crannies and some big groupers here too. Look up and you might see schools of fusiliers or turtles swimming past.
Koh Nang Yuan - The small islet of Koh Nang Yuan is connected to Koh Tao by a thin strip of white sand and is surrounded by several charming dive sites. It's an area for relaxed and easy scuba diving and is also a very popular place for snorkelling as there are plenty of reef fish. Show more
Green Rock is a big boulder formation located on the north west of Nang Yuan Island. The dive site starts at about 1 metre below the surface and goes down to a depth of 30 metres. Green Rock has an impressive number of swim-throughs and overhangs which are the highlight of the site where you can expect to see moray eels, blue-ring angelfish, blue damselfish, groupers, batfish and sea snakes. It is also infamous for rather aggressive yellowmargin triggerfish and titan triggerfish.
Located between Koh Nang Yuan and Koh Tao, Nang Yuan Pinnacle is like a miniature version of Sail Rock. It is only a few fin kicks away from the eastern coastline of Koh Tao and starts at just 2 metres below the surface. There are many interesting boulders with nooks and crannies to explore here, and several swim-throughs. Moorish Idols, angelfish and oriental sweetlips are some of the common inhabitants. Also keep an eye out for octopus hiding in the rocks and cuttlefish.
Twins is just south of Koh Nang Yuan. It is a similar dive to White Rock on Koh Tao and is actually 2 rock reef patches starting at 6 metres and going down to 18 metres. There are lots of anemones here with their resident families of clownfish.
Shark Island - is a small rocky islet off the southeast coast of Koh Tao. The eastern side is the more interesting with its boulder formations. Many types of tropical fish are found around here. On the south side at 14 metres is a soft coral garden on a rocky bed. Sometimes you'll find leopard sharks and turtles here. Occasionally there can be strong currents at Shark Island from either the southeast or northwest.
Southwest Pinnacle is approximately 13 km south west from Koh Tao and in many ways it is like a shallower version of Chumphon Pinnacle. It's best to dive here when the Gulf sea is calm as Southwest Pinnacle is out in the open and has no protection from waves, but it is well worth the effort as it is one of the best dive sites at Koh Tao. Show more
The dive site consists of a limestone rock and boulder mount that's completely submerged and carpeted with pink and gold anemones and their host spinecheek anemonefish. Surrounding the rock formation are black corals and sea fans. Leopard sharks, blue-spotted sting rays and marble groupers are often found here on the sand substrate bottom.
Whale sharks can sometimes be spotted here and it is also popular with juvenile pelagic fish such as yellowtail barracuda, schools of reef fish such as yellow snappers and rabbitfish, and bigreef squid.
White Rock - The site is located mid distance between Koh Tao's Mae Haad Pier and Koh Nang Yuan. The site consists of 2 large boulders which are only a few metres apart. These big stones are surrounded by smaller boulders and patches of coral. The site is a relatively easy one with the maximum depth around 20 metres. The star of the show at this dive site is Trevor the Triggerfish who is known as the most aggressive triggerfish at Koh Tao.
The dive sites can be visited on day trips from Samui Island. Dive boats depart every morning, normally in quite small groups. You will normally return at 5:00 pm in the early evening. You can book dive day trips only, or combine them with accommodation at one of our recommended Koh Samui resorts.
The dive sites around Koh Tao can be visited throughout the year. The water is an average temperature of 28-29°C. However, the best season for optimum conditions is from March to September, with the busiest months being July and August. The weather during this period is warm and usually sunny, offering the best conditions for diving, especially in terms of underwater visibility.
Monsoon winds reduce visibility from October to November, and sea swells can be present. However, these are rarely bad enough to interfere with the running of diving trips.
November to February brings rain and winds to Koh Tao so it is not be the best place to be at this time of year.
There is a chance to see big pelagics such as whale sharks, most often in September, but the possibility remains all year around. Titan triggerfish might become aggressive during their breeding season which usually runs from March to April, as they are extremely territorial. The male usually guards the nest against intruders, including scuba divers. They are only following their instincts and divers should avoid getting inside their 'protection zone' (above the nest, as the titans can see upwards).
A positive aspect of Koh Tao is that, being a small island, it is possible to travel around it by boat in less than an hour, visiting the best dive sites that each day has to offer, in terms of conditions and marine sightings. Additionally, Koh Tao's small landmass means that growing rain clouds unleash their rains over the larger neighboring islands of Koh Samui, Koh Phangan or the Thai mainland.
Good for: Large animals, beginner divers, dive value-for-money and snorkelling
Not so good for: Wrecks and drift dives
Depth: 5 - 35m
Visibility: 5 - 20m
Currents: Usually gentle but can be strong at some sites
Surface conditions: Normally calm, but can be choppy offshore
Water temperature: 27 - 30°C
Experience level: Beginner - intermediate
Number of dive sites: ~15
Access: Koh Samui diving day trips
Recommended length of stay: 5 days