Kompong Som , formerly Sihanoukville , city and seaport (1994 est. pop. 75,000), located in but politically independent of Kampot prov., S Cambodia, on the Gulf of Thailand. Although a new city (completed 1960), it is the principal deepwater port and commercial outlet of Cambodia. The city and port were built on mud flats, with French aid, and grew with the construction of a highway and railroad to Phnom Penh. Kompong Som has an international airport.