Richelieu Rock is one of the best places in the world to dive with whale sharks and is easily the best site in Thailand diving for this amazing activity. Here divers will encounter the largest fish in the ocean which are rare almost everywhere in the world. With nothing else for miles around, the whale sharks are attracted to the rock to feed on the rich plank tonic blooms that occur here.

• Dive Type: Boat Dive
• Diver Level: Novice Diver - 20 + Dives
• Max Depth: 40m

Koh Tachai is located in Tachai Island and lies about halfway between the Surin and Similan Islands and is rated as one of the best sites for Thailand scuba liveaboards as it's normally visited on the way to Richelieu Rock from the Similans. There are several dive sites around the island but the most famous is Koh Tachai Plateau which lies southeast of the island, about one kilometre offshore. The plateau is a submerged crowned reef of hard sheet corals, and scattered boulders. These boulders provide great swim-throughs and cut-through opportunities.

• Dive Type: Boat Dive
• Diver Level: Advanced Open Water Diver
• Max Depth: 35m

This dive site is one of the best places in Thailand to see manta rays, especially from April to May.
Koh Bon Island lies an hour or so north of the Similan Islands. It has a 33 metre wall on its south side, facing a small cove, with a stepped edge pointing west and down to over 40m.

Here divers will have the opportunity to see leopard sharks, white tip sharks; soft corals the colours of turquoise, yellow and green dominate. If you listen carefully you'll hear the warning clicks of hundreds of nervous damselfish, and the coral crunching of hungry titan triggerfish.

• Dive Type: Boat Dive
• Diver Level: Novice Diver - 20 + Dives
• Max Depth: 40m

This is one of the most colourful, scenic and often exciting dive sites in the Similan Islands. The dive begins at Christmas Point by heading down a mooring to a sand-rubble bottom at a depth of about 20 metres, then heading deeper to the southwest where divers will find several giant arches and some of the best swim through in the Similans. The rock walls are highlighted by radiant soft corals and the sea fans can be very large here. Here divers will have the opportunity to see ribbon eels and fire gobies, and check the sand plains beyond the arches for white tip or leopard sharks.

• Dive Type: Drift Dive
• Diver Level: Novice Diver - 20 + Dives
• Max Depth: 40m

The site is named after an unusually shaped rock that juts out of the water just southwest of Koh Similan. The huge boulders that form Elephant Head Rock create daring swim-through, arches, caverns, gullies and tunnels. Here divers will have the opportunity to see fronds, colonies of spiders crabs, large black egg cowries, cuttlefish and mantis shrimps as you sink further down to entrance floor.

• Dive Type: Boat Dive
• Diver Level: Novice Diver - 20 + Dives
• Max Depth: 45m

The Shark Fin Reef will offer diver two different sceneries. The northeast which features a sloping reef and the southeast which is a more dramatic drop-off. A series of parallel rocks resembling fallen logs are the setting for this Similan diving site.

To the southeast is a large swim-through that provides an opening to the other side of this dive site. The marine life here is diverse with clown triggerfish, half-moon triggerfish and schools of batfish, palette surgeonfish, blue-faced angelfish and banner fish. It's also a good place to spot passing sharks and larger rays.

• Dive Type: Boat Dive
• Diver Level: Novice Diver - 20 + Dives
• Max Depth: 40m

The Thai name for this spectacular rock is “Hin Muan Deaw” and is the best way to describe how beautiful this rock really is, as it directly translates to “Whole roll (of film) rock”, as one can use an entire roll film solely on this rock. Shallow coral gardens comprise huge pore and staghorn corals with small pinnacles. A big outcrop located on the southeast makes this dive site unique and attracts many photographers. Colorful soft corals, gigantic sea fans, and many species of hard corals surround this fantastic rock.

• Dive Type: Boat Dive
• Diver Level: Open Water Diver
• Max Depth: 18

West of Eden basically comprises giant granite boulders that create nice canyons, with walls covered with colorful soft corals and giant sea fans. Some areas are characterized by rubble and sand slopes. The shallows are home to many reef fishes, and have stacked granite boulders covered with hard corals, soft corals, gorgonians and feather stars. This area is a nice place to look for macro subjects like nudibranchs and frogfish. Keep an eye out for cleaner pipefish and many banded pipefish in small crevices, as well as long-nose hawkfish perched in black coral bushes. The rubble and sand slope are good place to search for ribbon eels, dragonets and red fire gobies. Back at the reef, moray eels are quite common, as well as turtles and schools of angelfish. Occasionally, whitetip reef sharks cruise by.

• Dive Type: Boat Dive
• Diver Level: Open Water Diver
• Max Depth: 18

Tachai Reef stretches through the eastern side of the island, going from the northeast to the southwest. Hard corals cover the entire area, most of which are staghorn corals, pore corals, brain corals, and fire corals. Divers regularly see leopard sharks lying at the outer sandy area and sometimes in shallow areas. Large stingrays are found on occasion too. General reef fish include pufferfish, lionfish, parrotfish, and moray eels. At night, several species of crabs and shrimp come out to hunt. It is possible to see twin-spotted lionfish, a rare species of lionfish that tends to be shy and hide in crevices. Cuttlefish, nudibranchs and flatworm are also common.

• Dive Type: Boat Dive
• Diver Level: Open Water Diver
• Max Depth: 18

Tachai Pinnacle or Twin Peaks are a pair of submerged pinnacles located 500 m south of Koh Tachai. The southern pinnacle is bigger and is a dome shape surrounded by large boulders. To the west you will find large boulders, some of which have formed swim throughs. In the east, you will find stacks of small rock, most of which are cover by hard corals and sea whips. Colorful soft corals and sea fans dominate the northern area. The top of the pinnacle is a wide flat plain with bush and mountain coral. The smaller pinnacle comprises of a wide range of rock clusters and is home to large sea fans and corals, which are similar to the ones found in the southern pinnacle.
Manta rays visit this area for feeding and circling around the pinnacles. Some divers have encountered whale sharks as well. On the outer sand bed, divers can usually see leopard sharks, sometime three to four of them in the same dive. In addition, it is possible to find Jenkin’s rays, as well as whitetip sharks and blacktip reef sharks here as well. Swarm of chevron barracuda, bluefin trevally, batfish, snappers, and fusiliers are common here.

• Dive Type: Boat Dive
• Diver Level: Open Water Diver
• Max Depth: 18

The wall, part of the Similan National Park, is decorated with various colorful soft corals and hard corals. From the ridge to the northeastern side are reefs that stretch along island. The reef slopes from a depth of 10m down to a sandy bottom at 25 - 30m. The majority of corals here are hard corals, including staghorn coral and brain coral that are interspersed with a few big coral heads. To the northwest of the island, there is a submerged pinnacle. The pinnacle is at a depth of 18 - 45m and is covered by an abundance of yellow soft corals and large sea fans. This site is a cleaning station for manta rays, so there is a high chance of finding at least one during a dive, particularly at the western ridge and northeastern outer reef. Koh Bon also has many kinds of sharks, such as leopard sharks and whitetip and blacktip reef sharks. Sometimes grey reef sharks swim by, and nurse sharks can be seen lying under coral heads. Schools of yellowtail barracuda, fusiliers, trevally, sweetlips and black and white snappers are all common in the area, as well as octopuses, sea snakes, and nudibranchs.

• Dive Type: Boat Dive
• Diver Level: Advanced Open Water Diver
• Max Depth: 45m