Ream National Park is home to some of Cambodia's most exquisite beaches, including those on Koh Thmei, a small island flanked by mangrove forests.
Koh Thmei is uninhabited, except for one set of bungalows and dozens of different species of birds. The beach next to the boat dock is a sea of thousands of glittering shells. The beach to the east of the dock is lovely pine-shaded yellow sand and if you get there early enough, you can catch a gorgeous sunrise.
Getting there: If you'd like to stay overnight, contact Koh Thmei Resort (Koh Thmei; T: +855 97 737 0400; koh-thmei-resort.com) to organize a taxi and boat from Sihanoukville. For a day trip, head to the Prek Toeuk ranger station in Ream National Park, where you can hire a longtail boat to the island.