The park covers 140 square kilometres in total, 14 of those being land in the shape of an archipelago consisting of nine islands. They are Ko Bon, Ko Bayu, Ko Similan, Ko Payu, Ko Miang (two adjoining islands), Ko Payan, Ko Payang, and Ko Huyong. For simplicity they are often referred to by their number instead - 1 through 9 starting from the south. Recently, 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 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.
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.
Location map Similan islands dive sites
On Koh Huyong, the Royal Thai Marines run a turtle breeding facility and access to the island is restricted.
High season in the Similans is from December until April, when the monsoon stays far away. The best period to visit is March, when the winds are calm and the water clear. The national park is closed from May 16 to November 15.
There are several dive trips going to the Similans from Phuket, Khao Lak and Ranong. Both day trips and live aboard cruises are available. Dedicated cruises usually start at 4 days and 4 nights (4d/4n) in length. Many shorter trips are available, often with operators who have a large vessel on the islands over summer and who do regular transfers using smaller speed boats.
Note that there is a national park entry fee of 400 baht per traveller and a further daily usage fee of 200 baht per diver per day. Most boats do not include this in their quoted price. It is paid to your dive operator before the trip.
Some diving liveaboard trips depart from Chalong or Patong. Most departures actually leave from Tap Lamu near Khao Lak but focus on the Phuket area, with offices in Phuket and pickups from major beaches
Dive Asia., 24 Karon Road, Kata Beach, 83100 Phuket, ☎ +66 (0) 76 330598, +66 (0)76 284117 (email@example.com, fax: +66(0) 76 521949, mob +66 (0)81 8948588), . Scuba diving and snorkeling trips, Richelieu Rock, Similan liveaboard trip, Richelieu Rock, Similan Islands, Surin Islands, Richelieu Rock liveaboard trip, Surin Island - Richelieu Rock liveaboard trip, Similan Island liveaboard trip, PADI course, package tours, dive equipment sale and rental.edit
Jonathan Cruiser, 43/63 Moo 5, Viset Rd., T. Rawai A. Muang, Phuket, ☎ +66 76 281529 (firstname.lastname@example.org, fax: +66 76 281530), . Jonathan Cruiser offers 4d/5n and 5d/6n liveaboard diving trips.25,000 baht for 4d/5n plus park fees and rental. edit
Peterpan Andaman Diving Co.,Ltd., 8/62-3 Moo 3 Kwang Rd. Tambon Vichit, Amphur Muang Phuket, ☎ +66 76 521948, +66 76 521949 (email@example.com, fax: +66 76 521949, mob +66 84 638 6668), . Scuba diving and snorkelling trip, Richelieu Rock daily trip, Surin Island daily trip, liveaboard trip, Burma (Myanma) liveaboard trip, Richelieu Rock, Burma (Myanma liveaboard) trip, Similan Islands, Surin Islands, Richelieu Rock liveaboard trip, Surin Island - Richelieu Rock liveaboard trip, Similan Island liveaboard trip, private cruise charter, wedding cruise charter, corporate event and party charter, PADI course, package tours, dive equipment rental.edit
Phuket Scuba Club, 241 Koktanod Road, Kata Beach, Phuket (Opposite Mom Tris Boathouse Hotel), ☎ +66 76 284026 (firstname.lastname@example.org, fax: +66 76 284026), . Regular Liveaboard departures from Phuket and available throughout October-May high season.edit
Scuba Cat Diving, 94 Thaweewong Rd, Patong Beach, Phuket, ☎ +66 76 293120 (email@example.com, fax: +66 76 293122), . Several liveaboard options are available. 3 cruise vessels do longer trips (4d/4n and up) to the Similan Islands and other destinations. The MV Scuba Cat is moored on the Similans throughout the high season with transfers by speedboat on Sunday, Monday, Wednesday and Friday. 2d/1n or extended stays are available. The lack of daily transfers has its upside: there won't be the bustle of divers arriving and leaving every single day.From 12,000 baht for 2d/1n. edit
South Siam Divers, 459/1 The Best Villa, Patak Rd, Karon, Muang, Phuket, ☎ +66 76 286016 (firstname.lastname@example.org, fax: +66 76 286020), . South Siam Divers has two boats moored on the Similan Islands, one with daily transfers and one with transfers 5 days a week (excluding Wednesday and Sunday). Daytrips through to living onboard for a week or more. The boat sleeps 28 and day trips are also possible, so during peak season there can be as many as 60 people on board for lunch between the arrival and departure of the speedboat. Divers are allowed 4 dives a day of 50 min each and must follow a guide.From 11,000 baht for 2d/1n. edit
Sunrise Divers, 269/24 Patak Rd, Karon Beach Phuket, ☎ +66 76 398040 (email@example.com, fax: +66 76 286130), . In Phuket since 1999, offers liveaboards and day trips to the Similan Islands on a wide variety of boats from backpacker style to more luxurious.edit
Thailand Divers, 198/12 Rat U Thid Road, Patong Beach, Phuket, ☎ +66 76 292052 (firstname.lastname@example.org, fax: +66 76 293034), . Liveaboards and day trips to the amazing Similan Islandsedit
Similan Dive Center™, 22/37 Moo 4, Khuk Khak, Takua Pa, Phang Nga (opposite Bangkok Bank in the center of Khao Lak), ☎ +66 76 485 792 (email@example.com). Open all year. Top service dive center with pick up service for Phuket for diving daytrips to the Similan islands and Koh Bon. Liveaboards from 2 days / 1 night to 4 days / 4 nights to the Similan Islands, Koh Bon, Ko Tachai and Richelieu Rock. Official Mares Dive Center with a large range of diving and snorkeling equipment.edit
White Manta Liveaboards, 18 Sin Ming Walk, #02-03, Singapore, ☎ +65 9677 8894 (firstname.lastname@example.org, fax: +65 6452 5496), . A Singaporean operator which has two vessels doing liveaboards in the Similans on the MV White Manta and the MV Black Manta. White Manta liveaboards are fairly high end, with the option of staying in luxury master suites with en suite bathrooms.4d/3n trips start at approximately 28,000 baht. edit
Khao Lak Explorer Dive Center, 4/81 Moo 7, Khao Lak, Takua Pa, Phang Nga, ☎ +66 76485308 (email@example.com), . Liveaboards and Daytrips to Similan Islands ,Koh Bon, Koh Tachai and Richelieu Rock from Khao Lak.Koh Phi Phi Liveaboard Daily departures for any duration.edit
Khao Lak Trip Dive Centre, 4/93 Moo 7, Khuk Khak, Takua Pa, Phang Nga, ☎ +66 76 485 297, +66 8 4638 6668 (firstname.lastname@example.org, fax: +66 76 485 296), . 4d/4n trip (up to 14 dives) to the Similan Islands, Ko Bon, Ko Tachai and Richelieu Rock.From 18,900 baht. edit
Manta Point Dive Center, 91 Moo 6, Khao Lak, Takua Pa, Phang Nga, ☎ +66 76 485 624 (email@example.com), . Operate liveaboards to Similan Islands and Richelieu Rock from Khao Lak. Daily departures for any duration.edit
Oktavia Dive Center, 70/4 Moo 5, Bang Niang (200 metres past Pinocchio Restaurant towards the beach), ☎ +66 83 634 0383 (firstname.lastname@example.org), . Owners and operators of MV Oktavia, one of the largest vessels cruising the Similan Islands for divers, snorkellers, and sun-worshippers alike.edit
Similan Dive Center™, 22/37 Moo 4, Khuk Khak, Takua Pa, Phang Nga (opposite Bangkok Bank in the center of Khao Lak), ☎ +66 76 485 792 (email@example.com), . Open all year. Khao Lak ecological dive center offers diving in a friendly atmosphere with an experienced crew. Day trips and daily departing liveaboards to the Similan Islands, Koh Bon, Ko Tachai and Richelieu Rock. Official Mares Dive Center with a large range of diving and snorkeling equipment. Operated by Khao Lak residents with over 20 years of experience in environmental research and diving.edit
Similan Diving Safaris, 13/19 Moo 7, Khao Lak, Khuk Khak, Takua Pa, Phang Nga, ☎ +66 76 485470 (firstname.lastname@example.org, fax: +66 76 485471), . From 17,800 baht (bunk in a 4-person room) for 4d/4n. edit
Thailand Dive & Sail (Khao Lak Dive Centre), 4/88 Soi Bang La On, Moo 7, Khuk Khak, Takua Pa, Phang Nga (on the side street leading to Banana Bungalows near the Viking Restaurant), ☎ +66 87 887 3878 (email@example.com), . Reliable, independent information and booking services for scuba diving, snorkelling and sailing trips to the Similan Islands.edit
Wicked Diving (Khao Lak Diving), 4/17 Moo 7 Khao Lak, Khuk Khak, Takua Pa, Phang Nga (adjacent to Viking Restaurant in the heart of Khao Lak), ☎ +66 76 485 868, +66 76 486 868 (firstname.lastname@example.org), . Khao Lak's only dive run to ethical and environmentally friendly standards. Operating two liveaboards offering 3 and 5 day expeditions to the Similan and Surin Islands providing for all diving skill levels. Also offer diving training, overnight tours and 3d/2n diving adventures with the nights spent on the the islands and days spent at various dive sites. 3d/2n trips depart on Monday and Friday.edit
Kon-Tiki Khao Lak Diving & Snorkeling Center, 13/128 Moo 7, Khuk-Khak, Takuapa, Phang Nga 82190, Thailand, ☎ +66 76 485378 (email@example.com, fax: +66 76 485378), . Daily diving and snorkeling trips to Similan and Surin island. PADI scuba diving courses and monthly IDC. Liveaboard to Similan islands, Burma Banks and Andaman islands.edit
Similan Scuba Adventures, 4/56 Moo 7, Tambon Khuk Kak, Amphur Takua Pa, Phang Nga, ☎ +66 76 485610 (fax: +66 76 485610), . Day trip where divers and snorkelers go to different sites to get the most out of the experience. They also have liveaboards.Day trip is €52 for snorkelers and €76 for divers (2 dives). edit
Similan Dive Center™, 22/37 Moo 4, Khuk Khak, Takua Pa, Phang Nga (opposite Bangkok Bank in the center of Khao Lak), ☎ +66 76 485 792 (firstname.lastname@example.org). Open all year. Daily departing snorkeling tours to the Similan islands, Surin islands and Koh Tachai. Two or three overnight trips at the Similan islands. Official Mares Dive Center with a large range of diving and snorkeling equipment. Operated by Khao Lak residents with over 20 years of experience in environmental research and diving.edit
Dive Safari Asia, 10/1 Moo 7 Khuk Khak, Takuapa, Phang-Nga, ☎ +66 805 269521 (email@example.com), . Fully inclusive dive tours featuring Similan and Koh Lanta National Parks, all transfers included.prices starting at 15,000 baht. edit
Lanta Diving Safaris, 289 Moo 1, Ban Saladan, Ko Lanta, ☎ +66 75 684904, . Ko Lanta's only liveaboard, does periodic (about 1 per month) 7d/7n trips that include a day's diving in the Similans.7d/7n trips approx 30,000 baht plus fees. edit
There are tours leaving from Khao Lak that offer diving and snorkeling tours. In addition, 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.
See the Stay safe section of the Scuba diving article for diving safety tips. Be aware that the islands are closed from mid-May to Early November of each year. Tour operators going to the islands during the closed times are not only risking your your comfort but safety.