Koh Rong Archipelago

The Koh Rong archipelago sits about 25km off Sihanoukville in the Gulf of Thailand, and it is a marginal dive destination that is honest about being one. Visibility is the defining limitation: the gulf here is shallow, silty and fed by mainland runoff, so inshore sites around Koh Rong, Koh Rong Sanloem and Koh Koun average roughly 10m and range from 5m to 25m depending on wind and rain.

Best time: Nov–Apr
Certification: Open water
Budget: $ · under $2,000

Trip length: 3–7 days
Trip style: Land based, Day trip, Liveaboard
Access: Moderate

The short version

Known forAmong the cheapest places in Southeast Asia to certify - a PADI Open Water course runs roughly $400-450 including boat trips and food.

Main tradeoffVisibility is the main problem, not a caveat.

Close-up of a seahorse gripping the seabed on a plain, dimly lit bottom

Photo: Mikhail Preobrazhenskiy / Unsplash

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Your outlook

Explore 7 dive sites

Browse the map and wildlife below, or add an optional preference to narrow Koh Rong Archipelago.

Most relevant wildlife

AnemonefishJan–May, Oct–Dec
LionfishJan–May, Oct–Dec
NudibranchJan–May, Oct–Dec
Bluespotted ribbontail rayJan–May, Oct–Dec

Plan the trip

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Loading dive-site map…

7 sites shown.

Conditions referenceSeason, water and visibilityBest Nov–Apr · Mild current · 27–32°C (coldest Jan, warmest Mar)

Best months Operating Closed / no trips

Current: Mild
Water temperature: 27–32°C (coldest Jan, warmest Mar)
Visibility: 5–25m: Inshore sites around Koh Rong, Koh Rong Sanloem and Koh Koun run 5-25m and average about 10m; 5m days are normal after rain or wind.
Experience: Most sites are 6-18m with mild current and suit newly certified divers - this is primarily a training and casual fun-diving area.

01 · Marine life

What you may see

rareoccasionalcommonly seenpeak seasondestination closed

Sightings are never guaranteed. The bars show typical likelihood by month.

AnemonefishAmphiprion spp.

Sighting likelihood by month
Month	Likelihood
January	commonly seen
February	commonly seen
March	commonly seen
April	commonly seen
May	commonly seen
June	destination closed
July	destination closed
August	destination closed
September	destination closed
October	commonly seen
November	commonly seen
December	commonly seen

Found year-round in the anemone patches at Two Tone Garden, Koh Koun and Koh Prins' Anemone Garden.

LionfishPterois volitans

Sighting likelihood by month
Month	Likelihood
January	commonly seen
February	commonly seen
March	commonly seen
April	commonly seen
May	commonly seen
June	destination closed
July	destination closed
August	destination closed
September	destination closed
October	commonly seen
November	commonly seen
December	commonly seen

Present year-round on the rocky reefs and sponge slopes around Koh Rong Sanloem.

NudibranchNudibranchia (order; multiple species)

Sighting likelihood by month
Month	Likelihood
January	commonly seen
February	commonly seen
March	commonly seen
April	commonly seen
May	commonly seen
June	destination closed
July	destination closed
August	destination closed
September	destination closed
October	commonly seen
November	commonly seen
December	commonly seen

The most reliable thing to look at here.

Bluespotted ribbontail rayTaeniura lymma

Sighting likelihood by month
Month	Likelihood
January	occasional
February	occasional
March	occasional
April	occasional
May	occasional
June	destination closed
July	destination closed
August	destination closed
September	destination closed
October	occasional
November	occasional
December	occasional

Rays are among the more reliable sightings on the sand flats, especially at Koh Tang's Stingray Alley and the Koh Prins sand sites.

See all 12 species

Giant moray Great barracuda Blacktip reef shark Cobia Pharaoh Cuttlefish Whale shark Spotted eagle ray Spotted Seahorse

02 · Dive sites

Dive sites worth knowing

A starting point, not a ranking. Conditions decide what works on the day.

Koh Koun

Koh Koun: Small island between Koh Rong and Koh Rong Sanloem with four shallow dive sites.

5–14m · Mild current

Koh Prins - Shark Point

The furthest-out site normally offered, on multi-day trips only.

5–30m · Moderate current

Cobia Point

Cobia Point: Underwater cliff face, the deepest of the inshore Koh Rong Sanloem sites at about 18m.

8–18m · Moderate current

See all 7 dive sites

Nudibranch Heaven Sponge Garden Two Tone Garden Koh Tang - Stingray Alley

03 · LogisticsGetting there and costsModerate. Fly to KOS. Typical trip $.

Route overview

Moderate

Reachable but with some friction: a 4.5h boat crossing.

Airport options

KOS

Sihanouk International Airport

Regional flights from Phnom Penh, Bangkok, Ho Chi Minh City and several Chinese cities; roughly 30 minutes by road to the Sihanoukville ferry pier

PNH

Phnom Penh International Airport

Cambodia's main international airport; about 4-5 hours by road or bus to Sihanoukville, or a short domestic hop to KOS

Typical trip cost

under $2,000

Per person, excluding international flights.

Cheap by dive-travel standards.
Scuba Nation on Koh Rong Sanloem lists a two-dive day trip at about $95 including equipment, lunch and boat, a Discover Scuba day at about $110, and snorkelling at about $30; PADI Open Water has been quoted around $445.
Overnight Koh Tang trips have been reported around $275-335 per person and Koh Prins around $325, including boat, food and dives.
Ferries from Sihanoukville run about $13-17 each way.
No marine park fee is charged to divers.
Prices are operator-published and change; confirm before booking.

Sources & last checked

Checked August 2026

Research is source-backed, but conditions and fees should still be confirmed locally.

View 13 sources and checking notes

Cambodia - Monsoonal, Tropical, Humid (Climate), Encyclopaedia Britannica
Anti-trawling Blocks Spark Marine Revival in Cambodia, CamboJA News
Seahorses in Cambodia, Marine Conservation Cambodia
Fishers left with no land, no fish, in fire sale of Cambodian coast, Mongabay
Boom to bust for Cambodia's Chinese casino town, Asia Times
Chinese Casino Pollutes Beach on Cambodian Island Near Sihanoukville, Radio Free Asia
Koh Rong Sanloem dive sites, Scuba Nation Diving Centre
Price List, Scuba Nation Diving Centre
Koh Tang, Wikipedia
Koh Rong (Cambodia) Water Temperature Today & Throughout the Year, Sea Temperature
Sihanoukville to Koh Rong Samloem ferry times and prices, Direct Ferries
Koh Tang Island List of Dive Sites for Scuba Diving, Private Scuba
Koh Prins dive sites, Scuba Nation Diving Centre

Note on the data: Confidence is low on purpose. Dive-site depths, names and marine life rest almost entirely on operator pages (Scuba Nation / divecambodia.com, The Dive Shop Cambodia, Private Scuba) - Cambodia has no dive-tourism research literature and no fetched government page. Site coordinates are approximate island-level positions, not surveyed GPS; Koh Prins in particular is placed from a rough bearing and distance description and should be corrected. Marine Fisheries Management Area area (405 sq km, 2016) and national park status (2018) come from research and NGO summaries, not a fetched Fisheries Administration document. Monsoon timing is well corroborated (Britannica: southwest monsoon mid-May to early October) but per-month sea-state data was not found. Water temperature is from a commercial sea-temperature aggregator, not a met agency. Operator claims of whale sharks 'in December and May' at Shark Point are coded rare with a caveat and should be treated as unverified. The national-parks.org page for Koh Rong Marine National Park returned 403 and could not be read. Water temperature: Warm year-round, roughly 28-31C average, with the minC and maxC values here taken from the source's published monthly extremes rather than dive-depth measurements; a 3mm shorty or rash guard is normally enough. Access: Sihanouk International Airport (KOS) to the Sihanoukville ferry pier is about 30 minutes by road; the speed ferry to Koh Rong or Koh Rong Sanloem takes roughly 45 minutes to an hour, while the offshore Koh Tang and Koh Prins sites need a 4-5 hour dive-boat crossing from the mainland (about 2 hours from Koh Rong Sanloem to Koh Tang) and are dived as overnight trips. Independently verified 2026-08-27: monsoon direction confirmed (SW monsoon mid-May to early Oct; calm Nov-Apr) against the US Library of Congress country study; Koh Tang crossing confirmed (7-knot boat, ~52km); MFMA 405 sq km June 2016 and the separate 2018 national park sub-decree (52,448 ha) both confirmed. Corrections applied: seahorse species was wrong (H. comes is not among the six MCC recorded — replaced with H. kuda), whale-shark dismissal was too strong (MCC logs ~10 sightings/yr), water temp maxima 33C unsupported (32C), trawling ban misattributed to a 20m depth rule.