The Surin Islands make up what is officially known as Mu Ko Surin National Park, and are home to one of the best diving sites in the world: Richelieu Rock. The islands are approximately 100km north of The Similan Islands, which makes them the northernmost Thai islands on the west (Andaman) coast. The border to Myanmar (Burma) is just 18 kilometres to the north. Access to The Surin Islands is controlled by government authorities and only possible from mid-October until mid-May. Dive centres based in Khao Lak visit The Surin Islands regularly during high season, either by liveaboard cruise or on speedboat day trips.
No diving trip to The Surin Islands would be complete without a dive at Richelieu Rock, but there are plenty of other fantastic places to go diving there, too. There are five islands in total, but the main two are Koh Surin Nuea (north), Koh Surin Tai (south), with Koh Ri, Koh Kai, and Koh Klang being just islets. Richelieu Rock is the same distance (18km) to the west of Koh Surin as Myanmar is to the north. The other dive sites are nearer to the islands, whereas Richelieu Rock is just an underwater pinnacle with no land nearby.
Richelieu Rock is regarded as the best diving site in Thailand. It is a horseshoe-shaped pinnacle which just reaches the surface from a depth of 30 metres. The site is full of life of all shapes and sizes, plus it receives regular visits from Whale Sharks and Manta Rays.
Boonsong Wreck is an old tin dredging wreck that sank thirty years ago. Its maximimum depth is 20m, so it's accessible to all. Visibilty isn't great, but doesn't detract from this diving wreck's appeal. It's not far from the mainland at Phang Nga. Actually, Boonsung wreck shouldn't be here in the Surin section, and we will move the page.
Koh Khai (Koh Torinla) is a small island to the south of the main two Surin Islands. It offers very nice diving, although not very deep. There's lots of healthy fish and coral, and it's well worth a visit for diving or snorkelling.
Koh Chi is a small island to the north of the main Surin Islands. The diving here is pleasant, yet not too challenging. It is constantly compared to its neighbour, Richelieu Rock, with which it cannot compete.
Chong Khat Bay is not really for scuba diving, because it is too shallow. However, snorkellers can enjoy lots of reef fish, in particular juveniles.
There are several other diving sites around the Surin Islands, some of which are preferred by certain boat captains and tour leaders. Ever-changing conditions and customer requests tend to influence the decision of which are visited on any given trip.