Similan Islands diving is the best in the world for most people

Many divers have their own opinion of what and where is the best diving in the world. And the factors to make their opinion may be seasonal or personal. If you take an objective look at things like dive sites, being suitable for all levels of scuba diver, logistics, cost, choice of trips and marine life, then Thailand’s Similan Islands is a worthy contender for being considered among the best. Similan Islands diving is the best in the world for most people not for one reason, but for a collection of all the important factors.

• Location
• What to see & do
• Who can dive there
• Popularity
• Similan Islands diving trips
• Getting there

Where & What Are The Similan Islands?

The Similan Islands is a small archipelago of uninhabited islands 60km. off of the west coast of southern Thailand. If you drew a straight line from Phuket northwest to the Andaman Islands, The Similans will be on that line but much near to Phuket than to the Andamans. Being located in tropical water far from any industrial areas or mainland, The Similans are surrounded by clear water with healthy coral reefs. Marine life includes residents of the reefs, as well as pelagic species which visit.

Physically, the Similan Islands are a small group of 8* islands and surrounding islets, but there are a couple more islands to the northeast which are included in the Similan Islands National Marine Park. These are Koh Bon & Koh Tachai. In addition, Thailand’s premier dive site is also nearby and visited on most Similan islands diving safaris (jump to types of trip). Richelieu Rock is technically part of the neighbouring Surin Islands National Marine Park, but most people combine Richelieu Rock with the Similans, in conversation as well as diving trips.

*The word ‘Similan’ means ‘nine’ in several local languages. For many years the Similans were considered to be nine islands, but one is so small, has no trees and at low tide is connected to its neighbour. Therefore, technically there are eight islands, although many sources will claim that there are nine.

Being located within National Marine Parks, the islands are protected and controlled by the local authorities. This means that certain activities (such as fishing) are prohibited. In addition, the parks are closed to the public for 5 months every year from mid-May to mid-October. The reason for this is mainly for public safety, because the monsoon winds from the Indian Ocean make the sea unpredictably rough. Also, having no visitors for 5 months goes some way to helping the natural ecosystem recover.

What is at the Similan Islands?

Accommodation : There are a few basic accommodation options for people who want to stay on the Similan Islands. However, it’s important to understand that anyone who stays on the Similan Islands does not and cannot scuba dive. The islands’ accommodation is controlled by the local authorities, and only simple activities, such as snorkelling, swimming and trekking along short nature trails are possible. The accommodation is simple bungalows and tents, which are located on Islands #4 & #8.

Beaches : There are several beaches at The Similan Islands, but it’s important to note that only two are open to the public. These are also on Islands #4 & #8. Island #8 is the most popular, as this is where the huge boulder is above the beach of Donald Duck Bay. Other beaches are closed to the public for various reasons which include protecting local turtles’ breeding areas, the royal family’s privacy, and most recently Koh Tachai’s beach was closed to give it time to recover.

From 9.30am until 3.30pm every day during the season (October to May) many day trip speedboats bring tourists to visit the Similan Islands’ beaches. And since May 2016 when Koh Tachai was closed, even more daytrippers visit Similan #4 & #8. Therefore, expect crowds of other tourists who also want to take photographs and enjoy the beach, snorkelling and climbing to the top of Donald Duck Bay. Those lucky enough to be on a Similan diving liveaboard can enjoy the beaches before the daytrip boats arrive or after they have left.

Marine Life : Most visitors to the Similan Islands come to see creatures under the surface of the crystal clear tropical waters. While most popular species are Whale Sharks & Manta Rays, these are never guaranteed. In fact, they are mostly sighted away from The Similans, at Koh Bon, Koh Tachai & Richelieu Rock. Turtles & Sea Snakes are reptiles often seen at most of the dive sites. Invertebrates range from tiny nudibranchs to octopuses. And of course there are many species of fish, some of which are solitary and others in huge shoals.

In recent years the coral has suffered some damage due to bleaching and the 2004 Asian tsunami. Both of these are natural phenomena. The reefs are considered to be healthy, and this is reinforced by the number of fish and other creatures that are seen there.

Who Can Enjoy Similan Islands Diving?

Every level of certified scuba diver can dive at the Similan Islands. There are plenty of individual dive sites ranging in depth, difficulty and what you can expect to see. In recent years some people did introductory dives at The Similan Islands, but the local authorities have changed the regulations. In order to prevent damage to the reef by divers who are unable to control their buoyancy, it is no longer possible to take your first breathes underwater at The Similan Islands. It is still possible to complete the Open Water Diver course at The Similans, and even take a Discover Scuba Diving introductory dive there. However, everyone must first complete training in a pool. This training enables them to learn the basic skills of scuba diving, in particular controlling buoyancy.

Which dive sites are suitable for particular levels of diver?

In general, the dive sites on the east side of the central Similan Islands are the easiest and can be enjoyed by any level of scuba diver. The eastern side of the islands are sheltered from waves and currents, and therefore have easier diving conditions. They also have more corals and small reef fish which make their homes here.

On the western side of the Similan Islands the currents and waves from the Indian Ocean have made a completely different type of dive sites, which are dominated by huge granite boulders. Some of these are better for experienced divers, but not all.

The southern and northern extremes of the Similans are also subjected to more currents and waves than the central areas.

Koh Bon, Koh Tachai & Richelieu Rock are not suitable for learning to dive. Although new & inexperienced scuba divers can visit these dive sites, they are more commonly enjoyed by more experienced divers who are able to descend to 30 metres and cope with occasional currents or surges.

How Many Boats & Dive Sites Are There?

There are lots of dive sites at the Similan Islands, meaning that it’s usually possible to find one that is not crowded with divers. It’s impossible to give an exact number of boats, simply because there are some which are there but not registered, as well as registered boats which are not operating.

Approximately 20 speedboats leave from Khao Lak every morning to take day trip divers and snorkellers to the Similan Islands. However, each has its own itinerary and therefore, they don’t all go to the same places at the same time.

At least 40 Similan liveaboard boats are registered to operate at The Similan & Surin National Marine Parks. Again they all have different itineraries, as well as separate schedules. This means that each dive site rarely has more than 3 or 4 boats moored at the same time. It’s quite common and easy to be on the only boat at a particular dive site. Richelieu Rock is Thailand’s best and most popular dive site, and there can sometimes be as many as 6 boats there at the same time. However, this dive site is huge and with divers getting in and out at different times, they’re also likely to be at different depths. Therefore, don’t be put off by the sight of several boats.

There are at least twenty separate dive sites at the Similan Islands, including Koh Bon, Koh Tachai & Richelieu Rock. The southernmost are at the tip of Similan #1 and the northernmost are at The Surin Islands.

Giving an exact number of dive sites is impossible to give because each captain, dive centre or cruise leader has his or her own opinion of which is which. For example, one person may separate two neighbouring dive sites whereas another may combine them in reference or even in one dive. There are no official names, and therefore this makes it even more complicated. Finally, from time to time the local authorities will close some dive sites and forbid anyone from diving there.

Southern Similan dive sites are those around Islands #1-3. Most day trip boats and liveaboards coming from Khao Lak do not visit Boulder City, Sharkfin Reef and their neighbours. This is because more time & fuel is required, and the dive sites are not ideal for inexperienced divers. However, the diving here is excellent and boats coming from or returning to Phuket often stop off here.

Central Similan dive sites are the most commonly visited. Here there is a wide choice of dive sites that can be enjoyed by all levels of scuba diver, and there’s plenty to look at above the surface. Boats can get shelter from the wind, and snorkelling between dives is possible. There are dive sites on both the east and west sides of the central islands.

Northern Similan dive sites are also very popular, especially because of Donald Duck Bay having a beach to visit. North Point and Breakfast Bend are just two dive sites located at Island #9.

Koh Bon has a couple of dive sites, but one (The Pinnacle) is far more popular than the other (The Ridge). In the bay Koh Bon Pinnacle is great for divers at a variety of depths. Here Manta Rays are commonly seen in water as shallow as 10 metres. Koh Bon Ridge starts deep and gets deeper. Therefore, it’s only suitable for experienced divers who can finish their dive in open water, possibly in a current.

Koh Tachai is a very beautiful dive site, made of huge boulders which are covered in all types of corals. Currents here can be unpredictable and sometimes strong.

Richelieu Rock is an underwater pinnacle in open sea far from the nearest land or island. This is the best dive site in Thailand.

The Surin Islands have some hidden gems. Here the dive sites tend to be shallower, but many corals are in excellent condition. 

Similan Islands Diving Trips

There are two main types of diving trip to the Similan islands, and each can then be separated into mini-groups. The two main types are day trips and liveaboard diving cruises/safaris.

Similan diving day trips nearly always have two dives, but one or two boats sometimes offer three dives. Due to the distance that needs to be covered there and back between sunrise and sunset, nearly all day trip boats are speedboats or catamarans with outboard motors. Some of the day trip boats take divers to large boats that are based at the Similan dive sites. They then dive from and eat lunch on the main boat.

Liveaboard trips are when guests sleep on the boats out at sea. They usually get up to four dives per day, including a sunrise and sunset or night dive. The length of each cruise depends on each boat’s schedule. 4D/4N (four days & nights) is most common, but there are plenty of longer and shorter options. Out of the liveaboard cruises some are ‘scheduled’ and others are ‘flexible.’ The scheduled trips leave and return with the same guests & staff on board. They usually depart in the evening and return in the afternoon 3-7 days later. Flexible liveaboard trips are when the main boat stays at sea and guests join for 2D/1N, 3D/2N or 4D/3N. The guests are transferred by speedboat in the morning of their first day and back in the afternoon of their final day. On flexible trips, guests and staff are continuously changing.

Getting to The Similan Islands

Getting to the Similan Islands can only be done on a pre-booked private tour, cruise or day trip. There are no public ferries. During the high season (December to February) nearly all trips are fully booked, and some are full months in advance. Therefore, it’s important to book your diving trip early. Some trips even offer a discount for early booking. Most boats depart from Khao Lak, but a few depart from Phuket. There are no day trip boats which depart from Phuket because the distance is too far.

Phuket has an international airport, and Khao Lak is an hour north by road. There are many transport options in southern Thailand, and prices are very reasonable. In addition, there are countless hotels in Phuket and Khao Lak. Therefore, staying in the area and getting out to the Similan Islands is much easier than many people think and much easier than some other destinations in Asia which may have better diving. It’s normally a compromise between the best diving, logistics and cost. The Similan Islands has the perfect balance of all three, and more.