You will have a totally free day to relax on the beach, swim in the clear waters and enjoy the peace of the area. Sihanoukville, also known as Kampong Som, is a province of Cambodia on the Gulf of Thailand. This port city is a growing Cambodian urban center, located 185 kilometers (115 miles) southwest of the Cambodian capital, Phnom Penh. Surrounded by white sand beaches and undeveloped tropical islands, Sihanoukville is the epicenter of beach life in Cambodia.