Koh Rong Sanloem is an island off the coast of Sihanoukville, Cambodia, 4 km (2 mi) south of Koh Rong. It is around 9 km (6 mi) long, 4 km (2 mi) wide and 1 km (1 mi) wide at its narrowest point. Its distance from the local port of Sihanoukville is 25 km (16 mi) (beeline) and 23 km (14 mi) (beeline) from the Serendipity/Ochheuteal beach pier. The word "Sanloem" translates to: 1. drowsiness and to: 2. far out and hard to discern, in a wider sense. Inconsistencies on how to spell the island's name in its Latinized version date back to the 19th century. The first controversial spelling variants were issued by map makers during French rule. Alternatives have since become widespread and are in common usage. Often confusion ensues as Google Maps offers the phonetically most consistent variant, whereas Google Search redirects to an alternative.

Sihanoukville, also known as Kampong Saom, is a coastal city in Cambodia and the capital of Preah Sihanouk Province, at the tip of an elevated peninsula in the country's south-west on the Gulf of Thailand. The city has a string of beaches along its entire coastline and coastal marshlands bordering Ream National Park in the east. The city has one navigable river, the mangrove-lined Ou Trojak Jet, running from Otres Pagoda to the sea at Otres. A number of thinly inhabited islands, under Sihanoukville's administration, are near the city.