The top attraction outside town is the coastal REAM NATIONAL PARK, which covers a range of habitats and has fine scenery and plentiful wildlife. Closer to hand are the Kbal Chhay waterfalls, a series of cascades fed by the Prek Toeuk Sap; these are fairly impressive in the rainy season, though there’s not much to see in the dry. To reach them, head out of Sihanoukville on National Route 4, turning left after about 10km at a sign for the falls, then continuing another 7km. A moto there and back costs around $8.
Unique in Cambodia, Ream National Park (also known as the Preah Sihanouk National Park) covers 210 square kilometres of both terrestrial and marine habitat, including stunning coastal scenery, mangrove swamps, lowland evergreen forest and the islands of Koh Thmei and Koh Ses. At least 155 species of bird have been recorded in the park, and for resident and visiting waders, the mangrove-lined Prek Toeuk Sap River is an important habitat. Besides supporting a large population of fishing eagles, the river is also home to milky and adjutant storks, and kingfishers, which are regularly spotted on the river trips. The list of mammals includes deer, wild pig and fishing cats, though these are all elusive and you’re more likely to see monkeys.