The Similan Islands, located about 50 Kilometers West of Khao Lak, are composed of nine granite islands washed by a clear blue tropical ocean and blessed with some of the world’s finest beaches.
Similan is a Yawi or Malay word, which means nine or a group of nine islands. In 1982, this 128 square kilometres area was declared a marine national park, and in recent years this group of nine small islands has become one of the leading attractions for visitors to Southern Thailand.
With the establishment of stations by the Royal Forestry Department on Koh Miang and Koh Similan, fishing within the national park boundaries was banned and the unwanted visitors were substituted by tourists, especially after 1987, when leisure boats and dive operators started coming out on a regular basis.
Today Mu Koh Similan National Marine Park and all its reefs have recovered from earlier disturbances. Boats entering the Similan Islands National Park have to follow strict rules imposed and controlled by the national park officials, have to use the moorings prepared by the national park and use closed waste water systems to avoid any pollution.
Activities include
Diving, Snorkeling, birding, camping and lazing on the beaches. Many tour operators make visits to these islands. Please see our
links page for more information on agents we recommend.
Similan Island Information: Names
The nine Similan Islands are named from South to North.
The Southernmost island - Ko Huyong is also known as Similan Island #1Ko Payang also known as Similan Island #2Ko Payan also known as Similan Island #3Ko Miang also known as Similan Island #4 Ko Ha also known as Similan Island #5Ko Payu also known as Similan Island #6 Ko Hin Pousar also known as Similan Island #7Ko Similan also known as Similan Island #8Ko Bangu also known as Similan Island #9 is the Northernmost of the islands.
Part of the park, but geologically and physically quite separate are Koh Bon and Koh Tachai.
Ko Bon (Bon Island) - with no beach and no accommodation this is still an island to visit. A portion of the islands coral was destroyed by dynamite fishing before it became part of the National Park. It still holds some stunning scenery. This is also the most common site for sightings of Manta Rays.
Ko Tachai (Tachai Island) Tachai Island is located at the northern most tip of the park. There is a beautiful white powdered beach on the island. There are several
sites suitable for SCUBA diving. In addition there are several reefs suitable for snorkeling. Whale sharks and Manta rays are often found here during their seasons. Facilities incloud a freshwater source, campsites, a restaurant and small boats for snorkeling."Similan" comes from the Sea Gypsies. They speak a language similar to Malay. They named them “The Nine Islands” (Sembilan is “nine” in Malay). They designate the islands by names in Thai-and a number. The islands achieved national park status in 1981 and thus are fully protected under Thai law.
The National Park Authority maintains a residential center for Park Rangers and support staff on two of the islands: Ko Similan (Island #8) which is the largest Island and Ko Miang (Island #4), which lies mid-way through the chain. These are the only residents allowed on the islands, excepting the overnight guests.
Recently, the islands have come to the special attention of the Thai Royal Family which further assures protection of this national treasure. The Princess has had a "cabin" built on Island #4 and visits almost every year. The Similan Islands are famous for hosting some of the most beautiful beaches, snorkeling and dive sites in Thailand and are one of the better areas for diving in the entire world. One of the most fantastic characteristics of the islands is that we have two entirely different types of environments in one destination.
the rocky slopes of the Western Islands are barren and feature massive boulders and wind swept trees. The Eastern Side features the famous white sand beaches and coral reefs.
Similan Island information: WeatherThe monsoon play an important role in all apsects of life on the Similans. The monsoons always head in from the South West over the Andaman Sea. So The east coast is protected from the monsoons features powdery coral beaches, coral gardens of hard and soft corals which slope dramatically from the surface down to approximately 30-40 meters. Whereas the West coast is generally made up of the large boulders dropping intot he depths. The flora is very much affected by the constant winds and have very daramtic scenery with no beaches (The protected Donald Duck bay is the exception)
Thailand has three seasons; cool, hot and rainy. The best time to visit (for consistently great weather if you love the sun) is between October and May. The summer months of July and August are customarily very pleasant, although it tends to rain in the evenings. September is not usually the best time on the islands, as the seas are usually too rough for swimming (or diving) and rain fall is widespread.
With regard to water clarity on the Similan Islands, the water is actually more clear during the summer months; the islands are too far offshore to be effected by freshwater run-off
Diving and snorkeling is usually equally nice in the summer months, but it may be a good idea to carry some rain gear like a poncho for transportation between the boat and the car! It's also very difficult to make it to the Similan Islands due to winds and waves. There are no day trips running. Be very WARY of companies that offer Day trips during these months. One shop in Khao Lak (Thai owned and operated) has sunk their Speedboat operating in the monsoons.
Monsoons are the major factor in the weather conditions. When they are gone, the Similans are open! Even the occasional thunderstorm presents more opportunity than harm - we just consider it air-conditioning.
There are seasonal variations in currents - as the prevailing winds that bring the monsoons also bring in colder waters from the open ocean we tend to have even clearer water. Tidal currents are strong at the narrow points in the islands and at the Northern and Southern Tips.
While conditions in Khao Lak (and to a lesser extent) are sometimes cloudy or rainy, the Similan Islands get less than 1/2 the rainfall that the mainland get.
Summer begins in mid February and ends in May. Rainy season starts from mid May till October with North - Western wind. Average annual temperature is 27๐c with average of approximately 83% humidity all year round. Average annual rainfall is measured at 3,560 millimeters with evaporation rate of 1,708 millimeters per year.
Similan Island Information: Monsoons
The northeast monsoon lasts from October until May and is considered to be the high season on the Similan Islands and in Khao Lak and is generally understood to be the best time of year for both traveling to and enjoying the Similan Islands. This is true to a certain extent, as the weather is consistent and predictable. The main reason it is the popular time, though, is that it’s winter in Europe and the States where most of our visitors come from, and people are escaping the cold.
During this time, since the wind is blowing from the northeast, on the West Coast of Thailand, boats can reach even the most remote of sites as strong winds don’t affect the sea until you reach far, far offshore. And, during the months of February, March, and April, the sea is generally flat and feels more like a lake than an ocean or sea. This is the transition time and it gets hot - 35 is not unheard of. The three months in the spring are hot here and the very best time for visiting the islands.
During the northeast monsoon, the wind can be very strong at times, 15-25 knots, so the Gulf of Thailand experiences fairly high waves and often times boats to Koh Samui or Koh Tao can not run due to the height of the waves. While that rarely affects the West Coast (Similans) it can cause some wind and even waves. Most reputable operators will advise guests of the risks (if any).
The southwest monsoon means the waves & wind now come from the southwest and since Khao Lak and the Similans face the west, the waves are hitting the West Coast beaches directly making the Andaman Sea feel more like an ocean rather than the glassy lake it usually is. Rain is more common which makes the country-side more green, tropical, and beautiful.
The Gulf, since it is protected for the most part from westerly winds, experiences flatter seas than Andaman Coast does during the southwest monsoon. However, it rains there just as much as it rains on the West Coast during that time.
The weather here is not severe. There are rarely typhoons or hurricanes or even severe tropical storms. Besides the constant heat here (and that’s not really a problem on the boats, islands or coastline) Khao Lak and the Similan Islands have some of the best and safest weather in the world.
The trick for visiting during these times is having protection from the waves. Unfortunately, many of the popular sites in the region do not have protection from rough weather. Since the sea height is unpredictable during the southwest monsoon on the Similan side, and unpredictable during the northeast monsoon on the Gulf side, it makes it difficult to plan trips to any areas that don’t offer proper protection from the waves. Thus trips toRichelieu Rock from Khao Lak are difficult since this site has little protection from the weather. Due to the distances involved in making trips to Burma (a 1,000km round trip), no one generally schedules trips to these areas during the southwest monsoon.
The main problem visiting the Similan Islands during the summer months, June until September, is the lack of people wanting to go--not that you physically cannot. At that time of year, people are traveling to more temperate climes rather than the hot tropics, so there are very few scheduled liveaboards during this time as boats can't get enough people together on a consistent basis. Almost every boat at one time or another has tried a summer schedule and few, if any, have ever been successful at it.
A couple of great links to help you see the current conditions....
Windguru gives a theoretical forecast of weather conditions.
And the
Thailand Meteorlogical Department also issues advisories and forecasts.
In Addition our friends at
Wicked Diving run a blog with frequent updates on conditions and diving on the Similans
Similan Island Information: Underwater geology
The monsoon play an important role in all apsects of life on the Similans. The monsoons always head in from the South West over the Andaman Sea. So The east coast is protected from the monsoons features powdery coral beaches, coral gardens of hard and soft corals which slope dramatically from the surface down to approximately 30-40 meters.
The base of these coral encrusted slopes is usually flat and forms a very nice transitional zone. The reefs are lush and teaming with life. Some very famous dive sites have been filmed and featured in many magazines and books -
East of Eden,
Breakfast Bend and
Beacon reef are among the most famous. Because of this incredible ecosystem, you will find most of the great snorkleing sites are on the East coast.Here, the most popular activity is drift diving along hard coral gardens while watching the reef inhabitants go about their business. At several sites, large coral bommies covered with soft corals and sea fans rise dramatically from the bottom. Here, the diving is easy and navigation simple, allowing each buddy pair to explore at their own pace. The Western coast of the Similans is typified by large boulder sites with steep drops. This is incredibly scenic and makes for incredible encounters as this is where the Pelagics (ocean going fish) come in to hunt. Frequent sightings of Manta Rays, Sharks, Barracuda and many more species make this side famous. This side is more exposed to currents and makes for more exciting dives and snorkeling. There are virtually no beaches on the West Coast (Donald Duck Bay is the main exception the this rule).
If you enjoy watching and photographing small fish the Similans are unrivaled for the sheer numbers and varieties of tropicals. Nudibranchs, Ghost Pipefish, Frogfish and lots of other small things make this a heaven on earth. For the Big Fish enthusiast - We Frequently see Manta Rays, Leopard Sharks, Reef Sharks (Black-Tip, White-Tip, Grey), Several kinds of Rays, Napolean Wrasse, Bumphead Parrotfish and lots more besides... Don’t expect big fish action every dive, just enjoy the Similans for what they are famous for: Wild, unspoiled beaches, magnificent coral growth, prolific marine life, crystalline blue water and sensational underwater rock formations.
