Today we are going diving in the Similan Islands, in the Phang Nga Province in Thailand!

Manta Similan Islands Thailand Vicki
A manta ray gliding along the Similan Islands. Photo courtesy of Vicki Hardwicke


The Similan Islands have an international reputation for being home to some of the most beautiful dive sites in the world. The Similan Island chain comprises of 9 islands and to the north there are the islands of Koh Bon and Koh Tachai. Further north is Richelieu Rock which is one of the best dive sites in the world.

The Similan National Park is only open from October to May each year but between the months of December to April it is common to see manta rays and whalesharks. The Similans is also a great macro diving destination.

Read Emma’s review of diving on a liveaboard at Richelieu Rock!

Close up Nudibranch Similan Islands
A great macro life destination. Photo courtesy of Vicki Hardwicke


Phuket is the closest airport to the Thap Lamu Pier where most Similan liveaboards depart from. Most liveaboard companies offer a transfer service and will pick up their guests from anywhere in Phuket or Khao Lak, including from the Phuket airport. From Phuket, it takes around an hour and a half to drive to the Thap Lamu Pier. 

Maldivian Soft Snail Koh Bon Vicki
A Maldivian Soft Snail at Koh Bon. Photo courtesy of Vicki Hardwicke


This is by no means exhaustive but moving from south to north, the most popular dive sites and the ones I do most regularly are:

Shark Fin Reef near Island #4 which is a drift dive, along a rocky ledge. Common to see white tip reef sharks here but like most Similans dive sites it is prone to strong currents and deep (40m)

Boulder City is also near Island #4 and consists of a cluster of granite rock boulders. Depth is around 30m.

Tuna Wreck on Similan Island #4 is a sunken tuna fishing boat which sits at a depth of 30m at the top and 35m at the bottom. It sits alongside a sloping hard coral reef where pygmy sea hares and harlequin shrimps have been found.

Tsunami Memorial is a dedicated memorial for the 2004 Boxing Day tsunami. There are a range of underwater monuments which have been erected. The monuments are within 10m however at 20m there is also an artificial reef worth visiting as ornate ghost pipefish have been spotted there.

Stonehenge is on the corner of Similan Island #4 and is another granite rock boulder dive site, you can easily reach 40m and there is often strong current here. Whalesharks have been spotted on this site.

West of Eden is on Similan Island #7 and consists of a hard coral reef and granite rock boulders. There is a nice sloping channel on this site which goes down to around 25m. There is also a resident frogfish on this dive site.

Deep Six is on the corner of Island #7 and consists of large rock boulders. Depth is around 30m and there is often strong current here. This is a good dive site for spotting reef sharks as well as lobsters which live under the rocks.

South of Eden is south of West of Eden and is a hard coral reef site. The site goes down past 20m but it is easy to stay shallow here on the reef. This site is prone to thermoclines though.

Frogfish Similan Islands
An elusive frogfish hiding out. Photo courtesy of Vicki Hardwicke


The only way you can really experience the Similan Islands is by staying on a liveaboard. Some operators used to offer day trips but I wouldn’t recommend those because it’s a lot of traveling and rushing around without seeing much. 

Overnight accommodation on the Similan Islands is now prohibited, so you can only sleep on a liveaboard. There are multiple operators with options for all budgets. All liveaboards provide beds, toilets, hot showers and meals. Some of the more expensive liveaboards provide their guests with private ensuite bathrooms, Nitrox and towels.

Different liveaboard operators offer different length trips; some depart and return to Thap Lamu Pier whereas others stay out in the Similan Islands and guests are transferred to and from the liveaboard and pier by speedboat which can take 60-90 minutes each way.

From Thap Lamu Pier it takes the liveaboard around 5 hours driving to reach the Similans Islands. Once on the Similans, to move between the islands, it takes only a matter of minutes. From Similan Island 9 to Koh Bon is around 90 minutes, from Koh Bon to Tachai is around 2 hours and from Tachai to Richelieu is around 3 hours.

Honeycomb Morayeel Boon Soong Wreck Vicki
Honeycomb Moray eel hanging out on the Boon Soong wreck. Photo courtesy of Vicki Hardwicke


The Similan Islands are prone to thermoclines which can be cold. Most rental equipment packages include a short 3mm wetsuit but if you feel the cold, it’s advisable to take more thermal protection. 

Items like reef hooks and gloves are prohibited inside the national park so divers are asked to keep these on the boat if they bring them. 

Most liveaboard companies will also include a torch for you if you choose to do a night dive, other companies charge 100THB for torch hire.


The Similan Islands are not really suitable for inexperienced Open Water divers due to the depth of the dive sites and the strength of the currents. Ideally, divers should have their Advanced certification or higher however it is common for divers to undertake their Advanced course during their liveaboard trip and undergo training during their dives.

As an Advanced diver, certified to 30m, you will be able to dive all dive sites. Due to the depth of the sites and the repetitive nature of liveaboard diving, an Enriched Air Nitrox certification is also useful. On most liveaboards it is possible to obtain this certification during your trip.  

Octopus Similan Islands
Octopi can be found in the Similan Islands…if you can spot them! Photo courtesy of Vicki Hardwicke


The water temperature is usually around 28 – 29° Celsius / 82.4 – 84.2°F. Thermoclines however can drop the temperature to as low as 20°C / 68°F. You can often see the thermocline before it reaches you because they are usually green. Most dive guides will try to avoid the “Green Monster” though.

Visibility can vary but is generally very good. 40m visibility is not uncommon in the Similans. If you do end up in a thermocline though, the water does turn green and the visibility does drop but this only lasts a few minutes before it is swept away. 

The currents in the Similans can be very, very strong and other than Shark Fin Reef and Three Trees, there aren’t many dive sites which allow the diver to drift. Consequently divers need some skill in navigating currents and using the dive site for shelter. Big currents do attract big fish though so this is when manta rays and whalesharks are often seen. 

The Similans season is from October to May each year. Usually at the start of the season the weather is still unstable so there can be rough surface conditions and surge. Around December it gets good and stays good until around April when the weather starts to turn again.  


Usually there are multiple dive operators running who offer a variety of packages to accommodate all budgets. Due to the closed borders in Thailand and the lack of tourists, not all liveaboard companies are operating this season so there is less choice. Saying that, there is also more competition for the boat companies to try and attract the few travellers there are here so many are offering discounts or special packages to try and out-do their competition. At the moment, a 4 day/4 night package on one of the more luxurious liveaboards costs around 28,000THB. This is all inclusive though and includes rental equipment, Nitrox, meals, towels, dive guide etc. 

Read More: Our predictions for the diving industry post-COVID.


The liveaboard operators vary in what type of accommodation they offer but even on the one liveaboard, there are normally options for different types of rooms you can choose to stay in. These options cater for all budgets and can range from a Queen-sized bed, to rooms with private ensuites, to twin share rooms, to bunk beds. There is a lot of choice. All rooms include air conditioning which seems to be standard on liveaboards.   


I work in the Similans so as staff, I either don’t get a room, or if I’m running the liveaboard, I get a bunk bed. The rooms for the guests are generally much nicer than what the staff get. Saying that, you’re there for the diving and spend a fair bit of time off the boat anyway, or in the common areas socialising so you’re not spending much time in your room anyway, other than to sleep. After 4 dives each day, it’s pretty easy to sleep and sleep anywhere. Even as a staff member, I’d recommend a liveaboard trip. You still have your creature comforts such as hot showers and real coffee and it’s a much more relaxed way to dive than doing a day trip or a shore dive!

Find out what a typical divemaster salary in Thailand is!

Close up of Barracudas Similan Islands
Chevon barracudas schooling. Photo courtesy of Vicki Hardwicke


If you’re a diver in Thailand and you haven’t been diving in the Similan Islands, you’re really missing out.

Richelieu Rock is Thailand’s most famous dive site and was discovered by Jacques Cousteu, it is one of the best dive sites in the world.

Liveaboard diving is also the most civilized and relaxed way to dive; you’re taken care of from the moment you’re picked up and looked after for the whole trip. There are long surface intervals between dives, there’s no rushing or over-crowded boats, you’re taken to the best sites and usually those where no other divers or boats are. The food is usually very good and there’s lots of it. Some liveaboards include free soft drinks.

Other boats include yoga and have movie nights, you can sunbathe, go onto the island and to the beach, you can snorkel between dives. It’s great!


When diving in the Similan Islands, you only really have one opportunity to step onto land and that’s at Similan Island 8. Usually you’ll have an opportunity to spend an hour or so at the beach and to climb Sail Rock for photos. There’s nothing really on the island now except for the National Park rangers so you need to take water bottles, sunscreen, towels etc. with you. 

When you’re not diving, you’re usually on the boat but there’s plenty to do. Some boats have card games and jenga, others have lounge areas with a range of movies. Most liveaboards serve alcohol at night, some even have disco balls and put on music. It’s very social. Guests normally don’t spend too much time in their rooms. 

I’m Vicki, from Australia. I’m a PADI IDC Staff Instructor and SSI Assistant Instructor Trainer. I’m also a technical diver, certified on trimix, CCR and am a full cave diver. I live and work in Thailand as a diving instructor. I have been in Thailand for 5 years now. I used to work permanently on a Similans liveaboard, which I did for two seasons; the first year as an instructor/guide and the second year, as the tour leader. My interests really only include diving. I dive every day; when I’m not working, I dive down at the local beach. My favourite creatures are nudibranchs and my life goal is to find each and every type before I die...only about 2,500 to go!