Richelieu Rock

Verified2026-09-11 checkedReefPelagicMacro

A horseshoe pinnacle in open sea, purple with soft coral, and the best whale shark odds in Thailand.

Depth: 5–35 m16–115 ft
Difficulty: Intermediate
Entry: Boat · Liveaboard
Typical current: Moderate
Coordinates: 9°22.002′N 98°1.998′E
Activities: Scuba

Richelieu is a limestone pinnacle that barely breaks the surface at low tide, sitting alone in open water near the Surin islands. The rock is covered in purple and pink soft coral and holds everything from tiny harlequin shrimp to schooling barracuda, which makes it rare in being both a macro and a big-animal site. Whale sharks pass through between February and April. Current varies around the horseshoe and the usual plan is to circle in its lee.

Liveaboard from Khao Lak or Ranong; too far offshore for a comfortable day trip.

Best season

ExcellentJan–Apr
GoodNov–Dec
FairMay

Before you get in

Past 30 m, where no-stop time and gas both go quickly and nitrogen narcosis starts to show.

Taken from this site’s recorded depth, type and current, and nothing else. An empty list is not a safe site — the sea on the day, the local geography and the boat traffic are not in it. The briefing on the spot comes first.

Conditions

Water temperature: 29.9°C86°F
Wave height: 0.2 m1 ft
Air temperature: 28.6°C83°F
Wind speed: 3.4 km/h2.1 mph

Updated 2026-10-07 15:45 UTC · Source: Open-Meteo

Weather data by Open-Meteo.com (CC BY 4.0)

Conditions are reported for information only. Assess the site yourself and follow your guide and your training.

No live conditions for this site yet.

We only show numbers we can attribute to a source.

Sea state and tide

On a date

Tide · 10/7

Low01:14-0.26 m
High07:241.33 m
Low13:45-0.52 m
High19:571.39 m

Forecast heights against mean sea level. Real tides in a bay, a harbour or over a flat can differ — check an official tide table before you get in.

Pick a day to see its tide

Only wave height and wind are scored, because those are what close a boat ramp or a shore entry. Water temperature is reported and never scored: 12°C is an ordinary dive in a drysuit and punishing in a 3 mm, and a number that cannot see your suit has no business marking it down. Stars do not decide whether you get in — you and your guide do, on the day.

Weather data by Open-Meteo.com (CC BY 4.0)

Marine life you may see

Soft coralDendronephthya spp.Common
Longnose hawkfishOxycirrhites typusRare
Whale sharkRhincodon typusFeb–AprSeasonal
Blackfin barracudaSphyraena qenieCommon
Harlequin shrimpHymenocera pictaSeasonal
FrogfishAntennarius spp.Common
Ornate ghost pipefishSolenostomus paradoxusSeasonal
Leopard (zebra) sharkStegostoma tigrinumCommon
TrumpetfishAulostomus chinensisCommon
PorcupinefishDiodon hystrixRare
Reef stonefishSynanceia verrucosaCommon
Titan triggerfishBalistoides viridescensCommon
Marbled stingrayTaeniura meyeniRare
Feather starCrinoideaCommon
Bluestripe snapperLutjanus kasmiraCommon
Yellowmargin triggerfishPseudobalistes flavimarginatusSeasonal

From divers

What people who were in the water reported. Not a forecast, and not a judgement about whether the site is safe to dive.

No recent reports from divers. If you dived here in the last two weeks, you can say how it was.

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