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North Andaman (Central Andaman Sea)

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Surin National Marine Park

Richelieu Rock

Richelieu Rock is a remote pinnacle in the Surin National Marine Park, located about 45 km off the mainland. Visible only at low tide, this horseshoe-shaped underwater formation descends to depths of up to 35 meters. Renowned as one of Thailand’s top dive sites, it’s named after Admiral Richelieu, former commander-in-chief of the Thai Navy.

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Surin Islands (Surin Islands)

The Surin Islands comprise two main islands—Koh Surin Nua (North) and Koh Surin Tai (South)—and three smaller ones, all part of the Surin National Marine Park. The two main islands lie just 200 meters apart and can be crossed at low tide. The park’s management office is located on Koh Surin Nua.

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Similan National Marine Park

Similan Islands (Similan Islands)

The Similan Islands, part of the Similan National Marine Park since 1982, lie about 100 km northwest of Phuket. The name “Similan” means “nine islands” in the local dialect, referring to the archipelago's nine granite islands, formed around 65 million years ago.

The islands feature dramatic landscapes, including a 233-meter peak and the iconic sailboat-shaped Hin Ruea Bai rock. Underwater, vast granite formations plunge beyond 40 meters, shaped into swim-throughs, caves, and canyons—creating a spectacular dive environment rich in marine life.

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Koh Bon (Koh Bon) & Koh Tachai (Koh Tachai)

Located in the northern Similan region, Koh Bon and Koh Tachai are part of the Similan National Marine Park. Koh Bon lies closer to the Similan Islands, while Koh Tachai sits nearer to the Surin Islands.

Koh Bon is known for its dark, volcanic-like rocks, while Koh Tachai showcases the rounded granite boulders typical of the Similan area. Both islands offer striking underwater terrain and vibrant marine life, making them top dive sites in the northern Andaman Sea.

Diving conditions in the Central Andaman Sea

This unique blend of dramatic granite formations and vibrant marine biodiversity makes the Similan Islands one of the world’s premier diving destinations. Massive granite boulders scattered underwater create striking seascapes, from colorful coral gardens to intricate rock formations.

The coral reefs here are among the most diverse and well-preserved globally, forming the foundation of the ecosystem. Built by tiny coral polyps, these reefs provide essential food and shelter for countless fish and invertebrate species, supporting a rich underwater world.

Diving season

The ideal diving season runs from December to March, offering the best weather and sea conditions. November and April are also good but can be less predictable. Limited diving is possible during the last two weeks of October and the first two weeks of May, though trips may be canceled due to rough seas or low bookings.

The Similan National Marine Park is closed from May 15th to October 15th each year. Visiting during this period is prohibited by law. The official tourist season is November 1st to April 30th.

Aquatic life

Marine Life Highlights

  • Large Pelagics: Manta Rays (Mar–May), Whale Sharks (Jan–Mar), Shovel-nose Rays, Eagle Rays, Guitar Fish

  • Sharks: Leopard/Zebra Shark, Nurse Shark, Bamboo Shark, White-tip & Black-tip Reef Sharks

  • Other Big Species: Bottle-nosed Dolphins, Green & Hawksbill Turtles, Sea Snakes, Giant Barracudas

  • Reef Fish & Predators: Clown, Oceanic & Titan Triggerfish, Oriental, Andaman & Harlequin Sweetlips, Napoleon Wrasse, Moorish Idols, Anemonefish, Boxfish, Pufferfish

  • Stingrays: Kuhl’s Stingray, Blue-spotted Stingray, Jenkin’s Stingray, Marvel Stingray

  • Colorful Reef Dwellers: Wrasse, Parrotfish, Humphead Parrotfish, Butterflyfish, Damselfish,
    Flying Gurnards, Long-nose Hawkfish, Lionfish, Scorpionfish, Stonefish

  • Unusual Creatures: Ghost Pipefish, Frogfish, Seahorse, Harlequin Shrimp, Nudibranchs, Giant Jellyfish

  • Cephalopods & Eels: Cuttlefish, Octopus, Moray Eels, Garden Eels, Peacock Flounder, Fusiliers,
    Giant Grouper, Snapper, Surgeonfish

Dive sites in the Central North Andaman Sea

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WHY SHOULD I BOOK WITH DIVE COVE ?

  • A Real Dive Center With A Real Shop

  • Dive Cove isn’t just a website. We’re a fully-equipped PADI CDC Center with experienced staff, top-quality rental gear, and deep local knowledge. We’re ready to assist you in person!

  • 22 Years of Thailand Diving Experience

  • With over 22 years of diving experience in Phuket, we’ve logged thousands of dives across the region. We know the dive sites, the boats, and the best spots. Trust us to find your ideal dive trip!

  • Liveaboard Price Guarantee

  • We offer official rates agreed with boat operators. If you find the same trip for less, tell us! We guarantee the best price for your liveaboard trip—no exceptions!

  • We Make Booking Liveaboards Easy

  • Booking with Dive Cove is fast and simple. Have questions? We’ve got the answers! Need assistance? Call us! We offer hassle-free online payments with no fees for most trips. We know the boats and the area inside and out!

WE HIGHLY RECOMMEND

AQUA LIVEABOARDS!

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