The large island of Koh Thmei is part of Ream National Park. It was once slated for a major development, including a bridge to the mainland, but as projects elsewhere have taken priority, this bird-laden island has remained miraculously pristine. There’s only one resort on the island, the expat-managed Koh Thmei Resort.
To get to Koh Thmei, make your way to Bat Kokir (Ou Chamnar), on NH4 about 12km east of Sihanoukville airport. All buses heading to or from Sihanoukville pass by Bat Kokir. Next, hire a moto (US$2) to take you 10km to the fishing village of Koh Kchhang. From here, Koh Thmei Resort can arrange private transport to the island, or negotiate in the village if you want to explore the island on your own.