Richelieu Rock — Richelieu Rock

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Hotels, dive operators, gear, and how to get here are on the Richelieu Rock location page.

Overview

Horseshoe-shaped pinnacle in open Andaman water, considered Thailand's best single dive. The whole structure is sheeted in purple and pink soft coral and anemones; whale sharks are seasonal regulars. Top of pinnacle barely breaks the surface at low tide.

Briefing note

Liveaboard-only access; closed mid-May to mid-October.

What you'll see

5 species curated

Whale shark
seasonal
Peak: Feb · Mar · Apr · May
Tomato anemonefish
year-round
Tigertail seahorse
year-round
Schooling barracuda
year-round
Cuttlefish
year-round

Sightings evidence

1 record on file

Whale shark
medium confidence
Last confirmed
May 2026
Recent records
45 within 25 km
Cluster months
Feb, Mar, Apr, May

Sources & methodology

How we summarise this

We aggregate confirmed occurrence records from GBIF and OBIS within a fixed radius of each dive site. Occurrence records confirm presence and reveal seasonality clustering, but they DO NOT measure per-dive probability — there is no eligible-effort denominator. We deliberately do not publish a numeric '% chance of sighting' from this data.

Sources

Global Biodiversity Information Facility — GBIF Secretariat
Ocean Biodiversity Information System — IOC-UNESCO
iNaturalist — California Academy of Sciences & National Geographic Society
IUCN Red List of Threatened Species — International Union for Conservation of Nature
Wildbook (Sharkbook, Whale Shark, Manta Matcher) — Wild Me
OBIS-SEAMAP — Duke University Marine Geospatial Ecology Lab / OBIS
WoRMS — World Register of Marine Species — Flanders Marine Institute (VLIZ)
FishBase — FishBase Consortium
Atlas of Living Australia — CSIRO / GBIF Australia
REEF Volunteer Fish Survey — Reef Environmental Education Foundation

Conditions

Month	Water	Visibility	Current
Jan	27–29 °C	20–30 m	moderate
Feb	27–29 °C	20–30 m	moderate
Mar	28–30 °C	25–35 m	moderate
Apr	28–30 °C	25–35 m	moderate
May	28–30 °C	15–25 m	moderate
Jun	28–30 °C	10–20 m	strong
Jul	27–29 °C	10–20 m	strong
Aug	27–29 °C	10–20 m	strong
Sep	27–29 °C	10–20 m	strong
Oct	27–29 °C	15–25 m	moderate
Nov	28–30 °C	20–30 m	moderate
Dec	27–29 °C	20–30 m	moderate

Season calendar

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Peak season highlighted · current month outlined

Gear for this site

Beyond the basic kit

SMB — Open-ocean pinnacle, all dives end with drift surface.
Reef hook — Hook in on up-current side to watch the action without finning.

Next step

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