Best Dive Sites in The Similan and Surin Islands

The Similan and Surin Islands are Thailand’s most celebrated diving destinations. Their granite boulders, coral gardens, and diverse marine life attract divers from around the world. Liveaboard trips usually combine the Similan Islands with the world-class sites of Koh Bon, Koh Tachai, and Richelieu Rock in the Surin National Park.

Best Season to Dive the Similan & Surin Islands

• Diving Season: November to mid-May
  (The Similan and Surin National Parks are closed from mid-May to October due to monsoon conditions.)

• Best Conditions:

  • December to April offers calm seas, clear water, and peak chances to see manta rays and whale sharks at Koh Bon, Koh Tachai, and Richelieu Rock.

  • February to April is particularly famous for manta ray encounters.

  • Visibility: Often 20–30+ meters, especially in January–March.

• Temperature:

  • Water temperatures range from 26–29°C.

  • Occasional thermoclines may drop temperatures to 24°C at deeper sites like Elephant Head Rock or Richelieu Rock.

Below you’ll find an alphabetical dive site guide, including depth ranges, difficulty levels, and seasonal diving advice.

Scuba Diving the Similan Islands 

Anita’s Reef (Island No. 4)

A classic Similan dive site with sandy slopes and scattered bommies covered in soft corals. Marine life includes bluefin trevally, shrimp gobies, blue damselfish, and yellowfin goatfish. Gentle currents make this a popular check dive at the start of a liveaboard.

• Depth: 5–25 m

• Difficulty: Beginner

Beacon Point

A sloping reef with hard corals, sponges, and sea fans. Divers can encounter turtles, lionfish, and moray eels, with the chance of stronger currents attracting larger pelagics.

• Depth: 8–30 m

• Difficulty: Intermediate

Boulder City (Island No. 3)

A submerged granite outcrop off Island No. 3, featuring large boulders on a sandy bottom. Conditions can be challenging, but divers may be rewarded with manta rays, whale sharks, nudibranchs, and macro life.

• Depth: 12–35 m

• Difficulty: Advanced

Breakfast Bend (Island No. 9)

A long, colorful reef ideal for drift diving. Expect butterflyfish, bannerfish, fusiliers, trevally, and the occasional tuna.

• Depth: 5–30 m

• Difficulty: Beginner–Intermediate

Christmas Point (Island No. 9)

On the western side of Island No. 9, Christmas Point is famous for its archways and swim-throughs. Look out for snapper schools, trevally, batfish, and reef sharks.

• Depth: 12–35 m

• Difficulty: Intermediate–Advanced

Coral Reef

A gentler reef with abundant staghorn and table corals. Divers often find stingrays, garden eels, and colorful reef fish.

• Depth: 5–18 m

• Difficulty: Beginner

Deep Six (Island No. 7)

A more advanced dive site with large submerged boulders, channels, and overhangs. Marine life highlights include barracuda, giant trevally, reef sharks, and moray eels.

• Depth: 10–35 m

• Difficulty: Advanced

Donald Duck Bay (Island No. 8)

Named for a rock formation that resembles the cartoon character, Donald Duck Bay is a popular night dive site. After dark, divers can see octopus, cuttlefish, crabs, shrimps, triton shells, and green turtles.

• Depth: 5–20 m

• Difficulty: Beginner

Elephant Head Rock

The largest pinnacle in the Similans, with dramatic arches, channels, and swim-throughs. Regular sightings include whitetip reef sharks, trevally, barracuda, frogfish, ribbon eels, and mantis shrimp. Strong currents make this suitable for experienced divers.

• Depth: 10–40 m

• Difficulty: Advanced

Fantasea Reef 

Fantasea Reef – Depth: 5–25m | Difficulty: Beginner–Intermediate | Best Season: Nov–Apr
A shallow and colorful reef known for its healthy soft corals, schools of fusiliers, and frequent visits from turtles. Calm currents make it ideal for beginners, while deeper sections offer plenty of interest for experienced divers.

• Depth: 5–25 m

• Difficulty: Beginner- intermediate

Hideaway (Island No. 5)

A calm reef dive ideal for spotting nudibranchs, lobsters, garden eels, and schooling reef fish.

• Depth: 5–18 m

• Difficulty: Beginner

Honeymoon Bay (Island No. 5)

A sheltered site often used for overnight anchoring. Known for garden eels, reef crabs, lobsters, cuttlefish, and nurse sharks on night dives.

• Depth: 10–20 m

• Difficulty: Beginner

North Point (Island No. 9)

Granite pinnacles with sandy bottoms and coral gardens. Look for leopard sharks, stingrays, barracuda, and macro species.

• Depth: 12–35 m

• Difficulty: Intermediate–Advanced

Shark Fin Reef

A ridge of granite boulders with excellent coral and sponge growth. Expect Napoleon wrasse, turtles, clown triggerfish, bannerfish, and boxfish.

• Depth: 10–30 m

• Difficulty: Intermediate

Stonehenge

Massive granite boulders give this site its name. Sandy patches host stingrays and garden eels, while trevally and fusiliers school nearby.

• Depth: 10–25 m

• Difficulty: Intermediate

Three Trees (Island No. 9)

A diverse dive site with sandy slopes, bommies, and coral gardens. Marine life includes reef sharks, stingrays, moray eels, nudibranchs, and seasonal manta rays.

• Depth: 10–30 m

• Difficulty: Intermediate

West of Eden (Island No. 6)

Also known as West of Six. Features healthy hard corals and granite channels. Expect batfish, turtles, ribbon eels, giant morays, and barracuda.

• Depth: 10–30 m

• Difficulty: Intermediate

Surin National Park & Beyond

Koh Bon

A steep wall and reef slope famous for its manta ray cleaning station. Divers drift along as mantas circle overhead. Other residents include Napoleon wrasse, reef sharks, and schooling fish.

• Depth: 10–35 m

• Difficulty: Intermediate

Koh Tachai (Twin Peaks)

A granite dome with strong currents attracting schools of barracuda, trevally, and batfish, as well as manta rays and whale sharks in season. Sandy areas host garden eels and stingrays.

• Depth: 12–35 m

• Difficulty: Advanced

Richelieu Rock

Thailand’s most famous dive site, a horseshoe-shaped pinnacle covered in purple soft corals and sea fans. Rich in marine life, from whale sharks and manta rays to seahorses, harlequin shrimp, and ghost pipefish. A must-dive for both big-animal lovers and macro photographers.

• Depth: 5–35 m

• Difficulty: Intermediate–Advanced

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