This dive site is found in the southern Andaman Sea. It is close to the Phi Phi islands but the dive site is normally accessed by liveaboard divers. The dive site is translated as five islands in Thai as it is made up of a cluster of small islets west of Koh Lanta Island. The dive site normally has great visibility and the dive site is found within the Mu Koh Lanta National Marine Park. They are uninhabited as well and so the marine life is left to its own devices. Unsurprisingly, the reef is known as having some of the most well conserved and most beautiful corals in Thailand and as a result, it is one of the most popular dive sites in Thailand.
On the largest of the five islets, there are a group of caverns, which are a fantastic part of diving here. They are safe for divers to enter as they have quite large and open entrances. Divers can also surface once inside the caverns and have a look at some of the stalactites hanging from the ceilings. These are ancient and have been here for many thousands of years. If divers are early birds, they can dive these caverns at sunrise, when the reflecting creates an emerald color in the cave.
There are also a number of swim throughs, and other parts of the reef to explore. Divers will find many kinds of marine life on this dive including reef fish, turtles, reef sharks, and pelagic fish such as mackerel and cobia. Moray eels and octopus are also common.
Koh Ha Yai is a group of five small islands about 32km (20 miles) south of Phi Phi Don. These sites offer regular visibility beyond 30m (98ft) and depths in excess of 50m (164ft). The draw cards of these sites are a couple of caverns that can be accessed in 10m (33ft) of water and allow you to surface inside to gaze at enormous stalactites, but there is a lot more than this to be seen, keep your eyes peeled for large tuna and even whale sharks. On the 20m (66ft) line rocky outcrops play host to massive gorgonians including sea whips. Another feature of these coral outcrops is the gargantuan shoals of silversides.