Dive Site: Richelieu Rock

About Richelieu Rock

Richelieu Rock, often celebrated as Thailand's premier dive site, is a majestic, isolated pinnacle located within Surin National Park in the northern Andaman Sea. Situated about 18 km east of the Surin archipelago and roughly 70 km northwest of Khao Lak, this unique site emerges above the surface only at low tide. The rock itself forms a distinctive horseshoe shape, featuring a central limestone pinnacle complemented by numerous smaller rock outcrops, all teeming with life. Its topography includes shelves, ledges, cracks, crevices, and small caves, providing a varied and dynamic underwater landscape. Jacques Cousteau reportedly named it after Cardinal Richelieu, inspired by the vibrant purple-red soft corals that adorn the rock, reminiscent of the cardinal's robe. This site boasts exceptional biodiversity, catering to both macro enthusiasts and those seeking pelagic encounters. The rock face is blanketed in an abundance of purple soft corals, vibrant hard coral bommies, and extensive anemone gardens. Divers frequently spot a huge array of smaller marine life such as porcelain crabs, tiger tail seahorses, various pipefish, robust ghost pipefish, mantis shrimps, harlequin shrimp, frogfish, leaf fish, and numerous nudibranchs. The deeper sections feature black coral bushes and gorgonians, offering shelter to an even wider array of creatures. The isolation of Richelieu Rock, coupled with tidal current upwellings, creates a rich feeding ground that attracts large schools of fish and substantial pelagic animals. Visibility here can range from 10-15 meters to an impressive 35 meters on clear days, with lower visibility often indicating higher plankton concentration – a key draw for larger filter feeders. Currents can be strong and changeable, making it an advanced dive despite shallow areas suitable for Open Water certification. It is frequently included in Similan Islands liveaboard itineraries, but day trips from Khao Lak are also popular. The dive experience at Richelieu Rock is multi-level, with depths reaching beyond 30 meters, offering ample opportunity to explore its diverse ecosystems.

Dive site facts: Richelieu Rock

Depth

5–36 m

Typical dive

12–25 m, 50–60 min

Current

Moderate to strong, variable

Visibility

20–30 m

Water temperature

28–30°C

Entry

Liveaboard / day boat

Level

Intermediate to Advanced, AOWD recommended

Dive type

Pinnacle, coral garden, macro, pelagic

Night dive

Not permitted

Region / port

Surin Islands National Park

Coordinates

9.3567, 98.0234

Conditions & Currents

Currents at Richelieu Rock can be strong and variable, a factor that influences dive conditions and visibility. Dive guides may opt not to dive certain areas during peak current days, even with experienced groups. Dive profiles here run between roughly 5 and 35 metres, so plan your gas and no-decompression limits around the deeper part of the site. It is usually briefed as a dive for advanced divers. Entry is from shore, so plan the swim out and back around the surface conditions of the day. Because the flow can pick up quickly, drift profiles, a surface marker buoy and a tight group are standard practice here, and the crew's briefing always overrides any general description.

Marine life & sighting chances

Whale shark

February to April · occasional

Manta ray

February to April · occasional

Giant trevally

common

Barracuda

common

Dogtooth tuna

common

Ghost pipefish

occasional

Harlequin shrimp

occasional

Tigertail seahorse

occasional

Nudibranch

common

Snapper

common

Batfish

common

Cuttlefish

common

Octopus

common

Lionfish

common

Dive profile & how the dive runs

Richelieu Rock is a horseshoe-shaped pinnacle with a central rock rising close to the surface at low tide. Dives typically begin with a descent line from the liveaboard or day boat, as the site sits in open water. Divers navigate around the pinnacle, exploring its various sections, ledges, and overhangs. The inner side of the horseshoe faces south, with depths generally ranging from 15 to 25 meters around the main structure. A satellite pinnacle lies to the east at approximately 26 meters. The dive profile involves exploring coral-encrusted walls and bommies, often moving with the current, which can vary significantly in strength and direction. Many dives involve observing the rich marine life on the reef, as well as scanning the blue for pelagics. Safety stops are often conducted in more sheltered areas or by ascending along the mooring line.

Underwater photography

Richelieu Rock offers exceptional opportunities for both wide-angle and macro photography. For wide-angle, a fisheye or ultra-wide rectilinear lens is ideal to capture the dense soft coral coverage, schooling fish like barracuda and snapper, and the dramatic topography, especially with seasonal whale sharks or manta rays. Utilize strobes to bring out the vibrant purple and red hues of the soft corals. For macro, the site is a treasure trove: look for ghost pipefish, harlequin shrimp, tigertail seahorses, and numerous nudibranchs among the corals and anemones. A dedicated macro lens with a diopter can be highly effective. Buoyancy control is paramount due to potentially strong and shifting currents; maintain a safe distance from the reef to avoid damage. Patience is key for capturing elusive critters, and a focus light is beneficial for intricate macro shots.

Combine with nearby dive sites

• Koh Bon

  Often combined in liveaboard itineraries, known for manta rays.

• Koh Tachai

  A popular liveaboard stop with diverse marine life and currents.

• Surin Islands — Turtle Ledge

  Part of the same national park, offering reef diving.

• Elephant Head Rock

  A Similan site featuring unique swim-throughs and pelagic action.

• Christmas Point

  Another Similan highlight known for rich coral formations.

Getting there & logistics

Richelieu Rock is situated within the Surin Islands National Park, approximately 60 km off Thailand's west coast and 18 km east of the Surin Islands. The primary access points are via liveaboard trips departing from Khao Lak or Phuket, typically lasting multiple days and often combining Richelieu Rock with the Similan Islands, Koh Bon, and Koh Tachai. Day trips are also available from Khao Lak, utilizing speedboats for a 1 hour 20 minute journey. These day trips typically include two dives and return in the late afternoon. Entry fees for the national park are required, and are often included in liveaboard or day trip packages. Booking in advance is recommended, especially during peak season, as trips can sell out.

Safety & environment

Diving at Richelieu Rock demands careful attention to safety protocols due to its open ocean location and potentially strong, unpredictable currents. Divers should possess excellent buoyancy control and be proficient in drift diving techniques. It is highly advisable to carry a Surface Marker Buoy (SMB) and a finger spool for signalling the boat in case of an unexpected ascent or separation. Dive guides are crucial for assessing conditions and planning the dive profile. The nearest recompression chambers are located in Phuket. Divers should ensure they have comprehensive dive insurance that covers emergency medical evacuation and treatment. Always stay close to your buddy and follow the dive leader's instructions, especially regarding current direction and entry/exit procedures. The site is generally not recommended for beginner divers due to its challenging conditions.

Who it suits — and who it doesn't

FAQ

Richelieu Rock FAQ

Liveaboards diving Richelieu Rock

These liveaboards may visit Richelieu Rock on selected itineraries — the exact dive sites depend on departure, weather and conditions.

Mandarin Queen 9

Thailand

26 guests37.5 m

Manta Queen 8

Thailand

24 guests

$127/day

The Junk

Thailand

18 guests33 m

$163/day

Deep Andaman Queen

Thailand

23 guests30.5 m

$194/day

Explorer

Thailand

16 guests25 m

$150/day

Andaman

Thailand

20 guests26 m

$108/day

Stingray

Thailand

8 guests24 m

$245/day

Seatopia

Thailand

24 guests24 m