In the midst of Indian Ocean, to the west of Thailand’s Phang Nga province lays the Similan Marine National Park. This group of islands is considered to be one of the top dive destinations in the world, mainly due to the wonders that await beneath the clear blue waters that surround the islands.
The Similans were designated the 43rd national park of Thailand in 1982 and cover an area of 128 km², including Koh Bon and the two rocky outcrops of Shark Fin Reef as well as Elephant Head Rock. In 1998, another 12 km² of Koh Tachai was added to the park, expanding the total area to 140 km², of which 15 km² island.
A solitary island located 20km north of Koh Bon, Koh Tachai has magnificent white sandy beaches with two interesting dive spots – Eastern Reef and the southern pinnacles known as “Tachai Pinnacles” or “Twin Peaks”, a pair of submerged pinnacles south of the island. It has varied and abundant marine life but is also well-known for the sometimes radically different colors of the coral. Manta Rays visit for cleaning sessions as well as to feed and circle around the area of the pinnacles. Divers can also encounter whale sharks, although sightings are rarer. On the outer sandy bed, divers can usually see leopard sharks, sometimes up to three or four of them on the same dive. In addition, it is possible to find Jenkin’s rays as well. Shoals of chevron and yellow tailed barracuda, bluefin trevally, batfish, snappers and fusiliers are common here. Exotic species in the Similans like, for example, oceanic triggerfish can also be found on the reef here.
Tachai Reef stretches along the eastern side of the island with the reef slope ranging from 5 to 30 meters and the site is covered with a variety of staghorn, brain and fire corals. In the southern part, the gentle slope becomes a steep drop off that heads to a depth of 30 meters.
Divers regularly see leopard sharks lying on the outer sandy area and sometimes in the shallower areas. Large stingrays are found on occasion too. General reef fish include pufferfish, lionfish, including one rare species of lion fish that tends to be rather shy and hides in crevices but is well worth seeking out. Cuttlefish, nudibranchs and flatworms are also common.