Ream National Park covers about 200 square kilometres of coast, mangroves, and lowland forest 20 kilometres east of Sihanoukville. Ranger-led boat trips up the Prek Toeuk Sap river take you through mangrove forest with kingfishers, monitor lizards, and proboscis monkeys; longer hikes climb into the dry forest behind.
The park headquarters is a modest building on the main road. Boat trips are best arranged on the day with the ranger station, although tours can also be booked from Sihanoukville. Bring water, sun protection, and insect repellent.