Cambodia’s islands sat in the shadow of Thailand for two decades, and that lag is exactly why they are interesting now. The Gulf of Thailand coastline off Sihanoukville holds roughly two dozen islands, and only a handful have been developed at all — which means the upper tier here is small, new, and priced below what the same product costs two borders west. This guide focuses on the Cambodian islands specifically for travellers who already know Thailand and Vietnam well and want the same water at a lower density of people.

The trade-off is honest: access is slower, the restaurant scene outside the resorts is thin, and wet-season logistics can genuinely disrupt a trip. What you get in return is beach frontage that would be wall-to-wall loungers anywhere else in the region. Below, the islands that actually support a luxury stay in 2026, what separates them, and who each one suits.

How Cambodia’s luxury islands compare

Four destinations carry the upper tier. They differ less on resort quality than on how much effort it takes to arrive and how much else there is to do once you have.

Rates above are dry-season doubles including breakfast, before the 10% VAT and service charges that most properties add. Wet-season pricing commonly falls 35–50%, which is the single biggest lever on cost if your dates are flexible.

Koh Rong Sanloem: the reliable choice

Saracen Bay is the crescent most people picture when they picture Cambodia. It faces east, which means sunrise over flat water and a bay that stays swimmable when the southwest wind is up. The resorts here are low-rise and spread along the sand rather than stacked, and the better ones hold 20 to 40 keys — small enough that the beach never feels worked.

Lazy Beach and Sunset Beach on the western side are a 20-minute walk over the ridge and give you the opposite exposure, which matters more than it sounds: in the shoulder months you can change which coast you swim on depending on the wind. Book east-facing for November through February, west-facing if you are travelling in the transition months.

• Water clarity is the best of the developed islands, typically 8–15 m visibility in dry season.
• Almost no road network, so transfers within the island are by boat or on foot — pack accordingly.
• Bioluminescent plankton is genuinely reliable here on dark nights, unlike most places that advertise it.
• Dining outside your resort is limited; half-board is usually worth taking.

Koh Rong: more island, more going on

Koh Rong is roughly four times the size of its neighbour and behaves differently. Sok San Beach on the west is the long, quiet stretch where the upper-tier resorts sit; Koh Touch on the southeast is the backpacker core and worth avoiding entirely if you are here for calm. The two are 40 minutes apart by boat and feel like different islands.

The argument for Koh Rong over Sanloem is optionality — there are restaurants, dive operators and boat charters that exist independently of the resorts, so a week here does not depend on one kitchen. The argument against is that you have to be deliberate about where you book, because the island’s reputation is set by a beach most luxury travellers will never visit.

The private islands: Song Saa and Koh Russey

These are a different product. Song Saa occupies two small islands joined by a footbridge, with overwater and jungle villas and a marine reserve it helped establish. Koh Russey (Bamboo Island) is a single-resort island with a longer beach and a more contemporary, pavilion-led design. In both cases you are buying the absence of anyone else, and the rate reflects that.

The practical question is trip length. Three nights on a private island is enough; seven can start to feel enclosed unless you are actively diving or the resort runs a strong excursion programme. A common structure is three nights private-island followed by four on Sanloem, which costs less overall than a week at the top tier and gives the trip some shape. If overwater accommodation is the draw, it is worth reading how to choose an overwater villa in Southeast Asia before committing, because the category varies enormously.

When to go, and when not to

Dry season is November to April. December through February is the reliable window — low humidity, calm crossings, water at its clearest — and it prices accordingly. March and April are hotter but still dry and noticeably cheaper.

May through October is the southwest monsoon. Rain typically arrives in concentrated afternoon bands rather than all day, so it is not a write-off, but sea state is the real issue: ferry cancellations become common and some smaller properties close for weeks at a time. The UK Met Office Cambodia climate summary is a reasonable reference for monthly rainfall and temperature norms if you are weighing shoulder dates.

Getting there without losing a day

Sihanoukville International Airport (KOS) is the gateway. Domestic flights from Phnom Penh take about 35 minutes and from Siem Reap about an hour; there are also seasonal regional connections. Overland from Phnom Penh is four to five hours by road, which is fine if you are already in the capital and want to avoid a short-haul flight.

Ferries depart from the Serendipity and Ochheuteal piers, with the last useful departure typically mid-afternoon — this is the constraint that catches people out. An evening arrival into KOS usually means a night on the mainland. Private-island resorts run their own boats on fixed schedules and will hold a transfer for a delayed flight if you tell them the flight number in advance. Current entry requirements and the e-visa system are documented on the official Cambodian e-visa portal.

How Cambodia stacks up against its neighbours

Against Thailand, Cambodia wins on crowding and price and loses on dining, transfers and the depth of the resort market. Against Vietnam, it is closer: Phu Quoc has better air access and a bigger hotel inventory, while the Cambodian islands have clearer water and far fewer people on the sand. If you are weighing Vietnam in the same trip, the Phu Quoc versus Nha Trang comparison covers that side of the border, and the dedicated Koh Rong resort guide goes deeper on individual properties.

For a wider regional frame, the Southeast Asia private-island roundup places Song Saa and Koh Russey against comparable buyouts in Indonesia and the Philippines — useful if seclusion rather than country is what you are actually shopping for. Marine-protected-area status for the Koh Rong archipelago is catalogued in the Protected Planet database, which is worth a look if reef condition factors into your choice.

Booking notes for 2026

• Confirm whether quoted rates include the 10% VAT and any service charge — presentation varies widely between properties.
• Ask specifically about wet-season closure dates before booking anything between May and October; some resorts do not publish them.
• Boat transfers are weather-dependent and rarely refundable through third-party sites. Booking the transfer directly with the resort gives you a human to call.
• Cash matters more here than in Thailand or Vietnam. US dollars circulate alongside riel, and smaller island businesses may not take cards.
• If you need connectivity for work, ask for the actual downstream speed rather than whether there is wifi.

Rates and transfer times are indicative for 2026 planning and move with season and availability. Verify each property’s current schedule, closure dates and cancellation policy directly before booking.