Mu Ko Similan are a group of nine small islands, with National Park status under the care of the Royal Forestry Department, in the Andaman Sea some 40 km west of Khao Lak. They are renowned the world over for their natural beauty
and incredible underwater sightseeing vistas at depths from two to thirty five meters.
Besides being blessed with some of the most picturesque white powdery sandy beaches one could ever imagine, with lush scenic flora inland, extremely huge
smooth granite boulders have been seemingly carelessly scattered around in the course of evolution to create a truly stunning scene. These same smooth formations cacsade and plunge into the azure clear warm waters to form seamounts, rock reefs
and dive-throughs, and the Islands' reputation as a world-class dive site is well deserved.
Inland the islands are essentially relatively low lying formations with some thick forest, sheltering the Nicobar pigeon, the hairy-legged mountain land crab, crab-eating monkeys, dusky langurs, bats, lizards and squirrels.
The word 'Similan' is derived from the Malay word sembilan meaning nine. Each island has both a name and a number. The Thais sometimes
refer to them as Ko Kao (or Nine Islands), and even the local fishermen refer to them by number rather than name.
Counting in order from the north, they are: Ko Ba-Ngu (No. 9), Ko Similan (No. 8), Ko Payu (No. 7), Ko Miang Sam (No. 6), Ko Miang Song (No. 5), Ko Miang (No. 4), Ko Payan (No. 3), Ko Payang (No. 2) and Ko Hu Yong (No. 1).
In addition there is a small rock outcrop between number 7 and number 8, known as Hin Pousar or Elephant Head Rock.
The Similan Islands exhibit the greatest variety and sheer numbers of reef fish in Thailand and exhibit at least 200 species of hard coral.
They provide a great deal of diversity for the diver, which is one of the reasons for their claim to fame.
In particular there is a general marked underwater contrast between the western and eastern sides of the islands.
The currents to the West have kept the huge, soft coral clad, granite boulders exposed, and free of sand, resulting in dramatic formations, peaks, canyons and overhangs to depths of 30m. These are quite exhilarating dives, and, for some, a guide is recommended to navigate the fan clad passages.
Currents on the west side can sometimes be unpredictable, and by late March in particular there are one or two upwellings (lasting only a few minutes at a time) of nutrient-rich water causing planktonic blooms. Perhaps
not surprisingly, deep-water creatures such as manta rays and whale sharks visit the area at this time of year.
On the Eastern coasts the boulders have been mainly buried as the fine sandy beaches slope down to reveal hard coral gardens. Here, the currents are gentle and much easier diving conditions prevail. There is a diverse and prolific mix of fish life, with a special colourful abundance of reef species.
The islands are largely uninhabited except for the Park HQ on Ko Miang ( #4) and a small ranger station on Ko Similan ( #8 ), both of which provide only minimal facilities and offer nothing for the diver.