Last Updated on May 31, 2025 by Dan
The Similan and Surin Islands, located in the Andaman Sea off Thailand’s west coast, are among the most famous diving destinations in Southeast Asia. Known for their crystal-clear waters, vibrant coral reefs, and abundant marine life, these protected national parks attract divers from around the world. Iconic dive sites such as Elephant Head Rock, Richelieu Rock, Koh Bon, and Koh Tachai offer a wide variety of underwater landscapes, from massive granite boulders to colorful coral gardens. Diving season is from mid-October until mid-May with visibility ranging from 20 to 30 meters and water temperature between warm and comfy 27-30 degrees Celsius.
Marine Biodiversity: Beyond the Giants
While the Similans are often associated with bucket-list sightings of manta rays and whale sharks, it’s important to have realistic expectations. These giants are incredible to see but not guaranteed on every trip. That said, lucky encounters still happen throughout the season—especially around Richelieu Rock and Koh Bon. Even without these larger species, the marine biodiversity in the Similan and Surin Islands is spectacular. Divers can expect to see reef sharks, turtles, schools of barracudas, batfish, and countless reef fish. The area is also a favorite among underwater photographers for its impressive macro life. Ghost pipefish, nudibranchs, harlequin shrimps, and even frogfish can be found with a sharp eye and an experienced guide.
Day Trips vs. Liveaboard Experiences
Many companies offer day trips to the Similan Islands from Khao Lak, with approximately four speedboats departing daily to visit the most accessible sites. These trips provide a quick glimpse of the area’s beauty, but they come with time limitations and less flexibility. While it’s a great option for divers short on time, it involves early starts, long boat rides and limited time underwater. For divers looking for a more immersive experience, liveaboards are undoubtedly the best way to explore these islands, as there are over 30 dive sites to see.
There are over 20 liveaboard operators departing from Khao Lak and around 20 more from Phuket. Liveaboards vary in length, comfort, and price, which makes it easy to find a trip that matches your budget, schedule, and vibe. Some boats attract a more youthful, social crowd, while others cater to divers seeking a more luxurious journey. For example, Khao Lak Scuba Adventures (KSA) runs the popular Manta Queen fleet, well-known among budget-conscious and younger divers for its fun and easy going atmosphere. On the more upscale side, Amity Diving Club offers a great boat, more upscale rental equipment and more comfortable liveaboard experience with spacious cabins and a relaxed more private setting.
Notable Options
Manta Queen Liveaboards (Khao Lak Scuba Adventures):
4 Days / 3 Nights (11 Dives) Price: Starting from 20,000 THB (~$590 USD) per person. Example: Manta Queen 2 offers a 3-night trip covering Koh Bon, Koh Tachai, Richelieu Rock, and Boon Sung Wreck.
6 Days / 5 Nights (19 Dives) Price: Starting from 31,000 THB (~$915 USD) per person. Example: Manta Queen 3 includes dives at Similan Islands, Koh Bon, Koh Tachai, Richelieu Rock, and Boon Sung Wreck.
Amity Diving Club – MV Koon 9 Liveaboard:
4 Days / 3 Nights (13 Dives) Price: 25,900 THB (~$765 USD) per person.
Day Diving with Wetzone Divers for those preferring day trips:
2 Dives at Richelieu Rock: price 6,500 THB (~$190 USD), Includes transfers, meals, and equipment.
Diving Regulations and Environmental Protection
All liveaboards and also day trip companies provide opportunities for continuing education with PADI or SSI courses, and according to Thai marine park regulations, divers must already be certified at least as Open Water divers before entering the Similan or Surin Islands. These rules are in place to protect both divers and the fragile marine environment. Groups are limited to a maximum of four divers per guide, ensuring safety and more personalized guidance. The dive guides in the Similan Islands are not only highly experienced but also incredibly familiar with each site—they know exactly where to find hidden creatures that others might miss.
Environmental protection is a priority in these marine parks. Operators and guides place strong emphasis on safe and eco-conscious diving practices. Divers are educated about the importance of not touching marine life or the reef, using reef-safe sunscreens, and avoiding equipment like reef hooks that could damage corals. These small but crucial practices help preserve the beauty and biodiversity of the underwater world for future generations.
Life Aboard: More Than Just Diving
Spending several days on a liveaboard is not just about diving—it’s a complete lifestyle experience. With up to four dives per day, you’ll have the chance to significantly improve your skills under the guidance of professionals. Between dives, there’s time to relax on deck, nap in the sun, and enjoy delicious meals freshly prepared on board. The atmosphere is fun and social, and many divers make lifelong friends during these trips. Sharing meals, dive stories, and sunsets with like-minded people is a special part of the liveaboard magic.
Post-Dive Adventures
After your diving adventure, Khao Lak offers a great place to unwind and explore a bit more of Thailand’s natural beauty. A trip to Khao Sok National Park, just a few hours inland, offers stunning limestone cliffs, jungle hikes, and the famous Cheow Lan Lake—perfect for a few days of kayaking or sleeping in floating bungalows. There are also several scenic waterfalls near Khao Lak where you can cool off and take a quiet nature walk.
Whether you’re a new diver eager to gain experience, a photography enthusiast hunting for rare macro subjects, or just someone looking to escape into nature and disconnect from the world for a few days, a liveaboard trip to the Similan and Surin Islands is an unforgettable adventure. With a wide range of boat options, professional dive guides, and spectacular underwater life, it’s easy to see why this region remains one of the top diving destinations in the world.
