The park covers 140 km2 in total. In 1998, the park was expanded to include the two remote islands Ko Bon and Ko Tachai, but since "Sembilan" is Malay for "nine" this doesn't seem to stick in people's minds and those are not visited as often as the original nine.
The park is an archipelago consisting of 11 islands, occupying an area of approximately 140 km2 with a land area of about 26 km2. For convenience, the Thai Department of National Parks (DNP) has assigned numbers to the islands. From north to south, they are:
- Island 11: Ko Tachai
- Island 10: Ko Bon, AKA Ko Talu
- Island 9: Ko Ba-ngu, AKA Ko Bayu
- Island 8: Ko Similan
- Island 7: Ko Hin Pousar
- Island 6: Ko Payu, AKA Ko Pa Yu
- Island 5: Ko Ha
- Island 4: Ko Miang, AKA Ko Meang. Park HQ is here.
- Island 3: Ko Payan, AKA Ko Pa Yan
- Island 2: Ko Payang, AKA Ko Pa Yang
- Island 1: Ko Huyong, AKA Ko Hu Yong
The islands were created by upwellings of hot magma during the Tertiary-Cretaceous period some 65 million years ago, then smoothed by glacial ice and the erosion by the sea. The coral reefs are about 5,000 years old and hence the oldest in Thailand. In 1982, the national park was established and now it is scheduled to become a UNESCO World Heritage Site.
The 2004 tsunami left the islands and the underwater landscape almost unharmed, since the waters are very deep around the islands.
The nine granite islands are postcard perfect images of paradise, covered in tropical jungle and equipped with beaches of chalk-white sand. As if this was not enough, the views under the water surface are even more impressive and many people believe this is the best dive site in Thailand. Skin-Diver Magazine has acclaimed the Similans to be one of the ten most beautiful places in the world.
Flora and fauna
There is an enormous diversity of fish species. Underwater visibility is the best you will find in Thailand. You will see plenty of colourful fish such as lionfish and clownfish (Nemo), and if you're lucky you may spot a bigger one like a manta or even a whale shark. The corals in the area have largely fallen victim to coral bleaching in 2010 and have not yet recovered, though the fish still make snorkelling and diving worthwhile.
On Ko Huyong, the Royal Thai Marines run a turtle breeding facility and access to the island is restricted.
High season in the Similans is from Dec-Apr, when the monsoon stays far away. The best period to visit is Mar, when the winds are calm and the water clear. The national park is closed from 16 May-15 Nov.
The Similans are closed to visitors during the rainy season, 16 May-31 October every year. In addition, Ko Tachai will be closed to tourism for an indefinite period starting 15 October 2016 to allow the island to recover from the destruction caused by excessive numbers of visitors.
Virtually every dive shop on the North Andaman Coast offers diving and/or snorkelling day trips and liveaboards to the Similans. Dedicated cruises usually start at four days and four nights (4d/4n) in length. Many shorter trips are available, often with operators who have a large vessel stationed at the islands who do regular transfers using speedboats. Consult dive shop listings in Khao Lak, Ko Lanta, Phuket, and Ranong, for information.
The national park admission fee for foreigners is 500 baht per day (children 300 baht). For Thai citizens the fee is 50 baht, children 20 baht. A diving fee is an additional 200 baht per day regardless of passport. Most boats do not include this in their quoted price. Fees are paid to the authorities via your dive operator before the trip.
Once on the islands there is the option of using the marine park boats for transit between the islands. This is not totally reliable, but is a less expensive alternative.
- Diving. Similan Islands diving is famous and high on the list of top dive destinations. The Andaman Sea has perfect water conditions that make underwater visibility extremely high and suitable for diving and snorkeling. The seawater has an average temperature of 25 degrees C.
- Mu Ko Similan National Park Souvenir Shop (Ko Similan). A small souvenir shop on Ko Similan sells small gift items.
- Mu Ko Similan National Park Restaurants (Ko Similan, Ko Miang). Daily when the park is open to visitors, 08:00-20:00. The facilities on the islands are pretty basic. You will find restaurants on Ko Similan and Ko Miang.
- Mu Ko Similan National Park Accommodations (Ko Similan), ☎ , e-mail: email@example.com. There are bungalows on Island 4 (Ko Miang): 20 air-conditioned room for two persons. The price is 2,000 baht; Ko Huyong Bungalows: five fan-only rooms for two persons. The price is 1,000 baht; Payang Bungalows and Payan Bungalows: Ten fan-only rooms for two persons. The price is 1,000 baht. Tents are available on Ko Miang, Ko Similan, and Ko Tachai. The tents are spacious for 2-3 persons per tent. The price is around 500 baht. 500-2,000 baht.
See the Stay safe section of the Scuba diving article for diving safety tips. The islands are closed from mid-May to mid-October each year. Tour operators going to the islands during the closed period are breaking the law.
The Surin Islands, which lie 40 km north of the Similan Islands.