Dive sites in Cambodia

Koh Prins lies approximately 25 kilometres south of the mainland coast near Sihanoukville. The boat ride takes about 90 minutes from the main pier, depending on conditions and vessel speed. This is significantly further than Koh Rong or Koh Rong Sanloem, which is why the site receives far fewer visitors. Most operators run Koh Prins as a dedicated full-day trip rather than combining it with closer sites.

Koh Rong offers easier access and more dive sites spread across its larger reef system, making it better for beginners and training dives. Koh Prins is smaller and further from shore but offers better macro life, more frequent bamboo shark encounters, and healthier coral on its western side. The visibility at Koh Prins can be more variable due to its exposed position. Experienced divers looking for quality macro diving will generally prefer Koh Prins, while Koh Rong is the better choice for a relaxed, accessible dive experience.

Yes, the southwest monsoon from June to October brings rough seas and reduced visibility that make Koh Prins inaccessible for most of the wet season. The best conditions occur from November to May, with peak visibility in February and March. Even during the dry season, conditions can be unpredictable, and operators may cancel the trip if seas are too rough for the longer crossing. The shoulder months of November and May offer good diving with fewer visitors.

Koh Rong offers a less polished but more adventurous diving experience than Thailand's popular islands. Visibility is generally lower than Similan Islands or Koh Tao, ranging from 5-15 metres, and the reef systems are smaller. However, Koh Rong's relative obscurity means far fewer divers, healthier fish populations in many areas, and a frontier atmosphere that Thailand's dive industry lost years ago. Macro life, particularly seahorses and nudibranchs, can be excellent.

Koh Rong is renowned for bioluminescent phytoplankton, particularly in the sheltered bays on the island's eastern coast. On dark nights with no moonlight, the water glows electric blue when disturbed — by swimming, splashing, or even trailing your hand through the surface. The effect is caused by dinoflagellates that emit light as a defence mechanism. It is most vivid during the dry season from November to May and is best experienced on moonless nights in calm, sheltered bays.