Koh Rong Island, along with Koh Rong Samloem Island next door, are Cambodia's largest, most popular dive sites. 40 minutes by speed boat from SihanoukVille, and 2 hours by regular dive boat, both islands offer an outstanding diversity of marine life. Not too much of the bigger fish, but much more variety than found elsewhere in Asia.
One Scuba Dive shop operates right on the Islands. The others come from the mainland of SihanoukVille, or from Koh Rong Samloem Island..., Some have bungalows right on the islands.
Most of the bungalows on Koh Rong Island have snorkeling gear for rent, or free for their guests.
Visibility is good around these closer islands, and even better further out from the mainland.