I swam in bioluminescent water at Koh Rong on my second night there. The plankton create small clouds of blue-green light when disturbed — your arms leave trails, your legs kick up sparks, and the darkness around you turns into something that doesn’t have a clean analogy. It was 11pm, warm enough that the water felt like the air, and there were about six of us in the ocean making blue fire with our hands.
That is the pitch for Koh Rong. It is not subtle, and it mostly works.
The two Cambodian islands — Koh Rong and the smaller, quieter Koh Rong Samloem (also spelled Sanloem) — offer something genuinely different from the Thai or Indonesian island circuit: lower prices, less infrastructure, a rawer quality to the experience, and bioluminescent plankton that remains one of the most reliable natural light shows in Southeast Asia. What they trade off is convenience, consistent power, reliable ferries in rough weather, and anything approaching resort-standard facilities outside of a few specific properties.
Here is how to understand what you are choosing between.
What Is the Difference Between Koh Rong and Koh Rong Samloem?
They are physically close — Koh Rong Samloem sits a few kilometers southeast of Koh Rong — but they attract different travelers and offer genuinely different experiences.
Koh Rong is the larger island, roughly 78 square kilometers, with a more developed main village and the most varied options for accommodation, food, and nightlife. The main settlement at Koh Toch Beach has a strip of restaurants, beach bars, and guesthouses along the sand that comes alive in the evening. 4K Beach on the western coast is more secluded and significantly more beautiful — fine white sand, crystal water, a handful of low-key bungalows — but requires either a 20-minute boat transfer from the main pier or a 90-minute jungle walk.
Koh Rong Samloem is smaller and divides into two distinct sides. Saracen Bay, the main bay facing east, has a long arc of white sand that is the most photogenic beach in Cambodia — calm water, turquoise color, the kind of beach that makes travelers rethink their prior reference points for what a beach should look like. The west side of the island has a few more isolated bungalows and near-complete quiet.
The overall atmosphere: Koh Rong has more energy and more nightlife. Koh Rong Samloem is calmer, better for snorkeling, and better for travelers who want to decompress rather than party.
Both islands have bioluminescence. Both are beautiful. The question is what you want to do with your days and evenings.
The Beaches
Saracen Bay on Koh Rong Samloem and 4K Beach on Koh Rong's western coast are among the finest beaches in mainland Southeast Asia — white sand, warm water, and very little between you and the horizon.
How Do You Get to the Cambodian Islands?
The gateway is Sihanoukville, and the ferries depart from Serendipity Pier (also called the new Ochheuteal Pier, depending on the operator). The pier is about 3 kilometers from central Sihanoukville.
To Koh Rong (Koh Toch village): Speed ferry approximately 45 minutes, around $12-15. Slow boat 2.5 to 3 hours, around $7-8. Multiple departures daily from the main operators (Buva Sea, Speed Ferry Cambodia).
To Koh Rong Samloem (Saracen Bay): Speed ferry approximately 35-45 minutes, around $12-15.
Booking: Tickets are available at pier kiosks on the day, or through guesthouses in Sihanoukville or Kampot. In high season (November-April), peak-time ferries can sell out — booking the day before is sensible.
Ferry cancellations: Ferries cancel without much notice when seas are rough, which happens most frequently in the wet season (June-October). Build extra days into your island schedule rather than booking ferries for the morning you need to catch a bus to Phnom Penh.
Getting to Sihanoukville: Direct bus from Phnom Penh takes 4-5 hours ($8-12). From Kampot, shared minibus or taxi takes about 90 minutes ($4-7). Giant Ibis is the most reliable bus operator for the Phnom Penh route.
When Is the Best Time to Visit the Cambodian Islands?
November to April is the dry season and the most popular time to visit. Seas are calmer, ferries are more reliable, rain is rare, and the water is clear. December and January bring the most visitors but the most consistent conditions.
May and June are the shoulder months. Weather is less predictable, some businesses reduce hours, but prices drop and crowds thin significantly. June is when the wet season begins in earnest.
July to October is wet season. Rain comes heavily and frequently, seas can be rough, and ferry cancellations become a real planning factor. Some accommodation on the islands closes entirely in September and October. The trade-off: prices are dramatically lower, the islands are quieter, and the bioluminescence is often most intense in these months (the plankton responds to warm water temperatures, which peak in wet season).
The bioluminescence exists year-round but is most visible on darker nights — the days around new moon are dramatically better than full moon. If this is a priority, align your visit with the lunar calendar.
What Should You Budget for the Islands?
Everything on the islands costs more than the mainland. Supplies, electricity, and food all arrive by boat, and prices reflect that.
Accommodation: Budget bungalows on both islands start around $20-35 per night in high season. Mid-range options (private bathroom, air conditioning) run $40-70. A few upscale properties exist on Koh Rong Samloem’s quieter side at $80-150.
Food: Beach restaurants run $5-10 per meal — simple grilled fish, fried rice, fresh seafood, Cambodian staples. Significantly cheaper than restaurant equivalents in Western countries but around 40-50% more expensive than equivalent meals in Kampot or Phnom Penh.
ATMs: There are no ATMs on the islands. Bring enough cash in USD to cover your entire stay plus a comfortable buffer for delays. Some guesthouses accept card payments but charge fees — assume you need cash.
Electricity: Generator-powered on most parts of both islands. Power is often limited to certain hours (typically 6pm-midnight or 6am-10pm, depending on the property). Charge devices during available hours.
What Are the Best Things to Do on the Islands?
Snorkeling: Koh Rong Samloem has better snorkeling, generally — clearer water around the rocky headlands and more intact coral. Bring your own mask and fins if possible (rental quality on the islands is variable). Ask your guesthouse about the current best spots — coral conditions change seasonally.
Island hopping: Both islands have boat tours that visit different beaches and snorkeling spots. A full-day island tour typically runs $15-25 and covers several beaches, a snorkel stop, and lunch.
Bioluminescence swimming: The best spots vary with tide and season, but on Koh Rong the bay near Koh Toch village is reliable, and on Koh Rong Samloem the calm water of Saracen Bay works well. Go late — 10pm-midnight — when boat traffic has stopped and the water is darkest. No torches or phone screens while in the water.
Jungle walks: Both islands have inland trails. The Koh Rong jungle walk from Koh Toch to 4K Beach takes about 90 minutes one way and passes through dense secondary forest. Take water, tell your guesthouse where you’re going, and use the trail — the jungle is disorientingly dense within a few meters of the path.
Doing nothing: This is underrated as an activity. The islands are built for it. A day of swimming, eating, reading, and watching the water change color in the late afternoon is a good day on Koh Rong.
Getting There via Sihanoukville
Sihanoukville is the ferry gateway to both islands. Otres Beach, two kilometers south of the main town, remains the most relaxed place to spend a transit night before catching the morning boat.
What About Sihanoukville?
Sihanoukville’s downtown changed dramatically during a period of heavy Chinese investment and casino development in the late 2010s. The original backpacker area bears little resemblance to what it was. Use Sihanoukville as a transit hub rather than a destination in itself.
If you need to overnight before catching an early ferry, Otres Beach — around 2 kilometers south of the main town — retains a more relaxed character. A handful of good guesthouses and restaurants there make it a better base than central Sihanoukville for an overnight stay.
Practical: Grab operates in Sihanoukville for getting between town, Otres Beach, and the ferry pier. The pier is not close to Otres — allow 15-20 minutes and book a Grab rather than negotiating with the local tuk-tuks outside the pier.
How to Pair the Islands with the South Coast
The natural routing is to combine the islands with Kampot and Kep: arrive in Sihanoukville, take a ferry to the islands for three to five days, return to Sihanoukville, then travel east to Kampot by minibus (about 90 minutes, $4-6) for a final few days of river cafes, pepper plantations, and the Kep Crab Market before heading to Vietnam or back to Phnom Penh.
This south coast loop — Phnom Penh → Sihanoukville → Koh Rong or Koh Rong Samloem → Kampot → Kep — is one of the most satisfying regional itineraries in mainland Southeast Asia. It moves between genuinely different environments without feeling rushed, and it introduces you to a Cambodia most visitors passing through on a Phnom Penh-Siem Reap-Bangkok circuit never see.
Book transport with 12Go Asia for buses and boats along the south coast route. For island guesthouses, Agoda covers most of the available options on both Koh Rong and Koh Rong Samloem.
If you are traveling between destinations and want emergency medical insurance that covers remote island situations, SafetyWing is the most practical nomad health option available.
Continue reading:
- Koh Rong — full destination guide
- Sihanoukville — the ferry hub and what remains worth doing
- Kampot — the riverside town to pair with your island days
- Cambodia’s South Coast: Kampot, Kep & the Islands — the full overland route
Plan your Cambodia island trip with the AI Trip Planner.