“Similan” is derived from the Malay sembilan, and means “nine”. Each of the Similan Islands has a number as well as a name. These are, running from north to south: Koh Ba Ngu (No. 9), Similan (No. 8), Payu (No. 7), Miang (No. 4, No. 5 and, in some opinion, No. 6), Payan (No. 3), Payang (No. 2), and Hu Yong (No. 1). Hin Pousar, or “Elephant Head Rock”, is alternatively designated No. 6 by some. Koh Bon, lying 17 nautical miles north of Ba Ngu, is part of the Similan National Park and may be granted honorary status as No. 10.
Ko Similan is the largest island. There are a total of 9 islands. The sea in the area has an average depth of 60 feet. Underwater it is full of rock formations and coral reefs in several shapes and forms, resembling such things as deer, leaves, brains, and mushrooms.
Above the water are found many diverse species such as the Nicobar pigeon, mangrove monitor lizards and more.
The Similan National Park is famous for its dive sites. It has typically two different kinds of diving. East side diving consists of gently sloping coral reefs with sandy patches with the occasional boulder in-between. The west side is known for its huge underwater granite boulders with numerous swim-throughs. Maybe the most famous east side dive site is East of Eden, off island number 7. Elephant Head Rock is arguably the most famous west side dive site with a maze of swim-throughs and the reputation for spin-cycle like currents running in every direction.
Elephant Head Rock was named by Horst Hinrichs from Germany in the mid-1970s, founder of one of the oldest dive shops in Phuket, Santana Diving.
Other popular dive sites include North Point, Deep Six, Boulder City and the awesome pinnacles off Ko Bon and Ko Tachai.