Clear water, beautiful sceneries above and under the surface, just the right amount of current… and of course, loads and loads of fish everywhere, how come we stayed so long without cruising the thai waters ?!
Diving the Similan Islands and Koh Tachai
The Similan Islands are among the best-known dive destinations in Thailand, and for good reason. Located in the Andaman Sea, the islands combine clear tropical water, dramatic granite formations and a remarkable variety of marine life. For divers, the underwater scenery ranges from colourful coral reefs and rocky pinnacles to swim-throughs, boulders and sandy areas where different species gather.
Our January 2015 trip was a great reminder of how rewarding diving in the Similan Islands can be. With relatively few boats around because of the windy conditions, we had some of the dive sites almost to ourselves — a rare treat at some of Thailand’s best-known dive sites.
What can you see while diving the Similan Islands?
The reefs are home to large schools of tropical fish as well as plenty of smaller reef creatures. Lionfish, moray eels, groupers, colourful reef fish and numerous invertebrates are common sights, while the open water can sometimes bring encounters with larger pelagic species.
And then there are the mantas.
Our guests were lucky enough to have a very special encounter with a large manta ray at Koh Tachai during this trip. The manta came back twice and stayed around for several minutes, giving the divers an unforgettable underwater encounter.
Koh Tachai is located north of the Similan Islands and south of the Surin Islands, and its exposed position can make conditions more challenging depending on the weather. When conditions are right, however, the area can offer spectacular diving and the possibility of encounters with larger marine life.

Exploring Thailand by liveaboard
One of the biggest advantages of a liveaboard is the amount of time it gives you underwater. Rather than travelling back and forth from the mainland between dives, you wake up at the dive sites and can spend several days exploring different reefs and islands.
From the Similan Islands and Koh Tachai to the Surin Islands and Richelieu Rock, the North Andaman offers a wide variety of diving. Conditions and itineraries vary throughout the season, but the combination of coral reefs, rocky pinnacles, schooling fish and occasional pelagic encounters makes this one of Thailand’s classic liveaboard destinations.
We have been exploring the Andaman Sea aboard The Smiling Seahorse since 2012, and Thailand remains an important part of our diving season alongside our expeditions to Myanmar’s Mergui Archipelago.
Want to explore the Andaman Sea with us?
Check our current Thailand liveaboard diving trips, itineraries and schedules to see when you can join us.
