Koh Thonsáy (Khmer: កោះទន្សាយ) is a Cambodian island located off the south western coast of Cambodia. "Koh Thonsáy" means Rabbit Island, and it is located close to the mainland of Kep City.
Koh Tonsay is located 4.6 km south of Kep and can be reached by boat from Kep port. Tourists are drawn to the beautiful white sand beach overlooking the sea. The sea here is shallow and the sea bottom has a long gradual slope, making Koh Thonsay excellent for swimming. At the sea bottom are a variety of corals, sea animals and plants which attract researchers and ecologists.
Koh Thonsay is 2 square kilometers in area. During Norodom Sihanouk’s Sangkum Reastr Niyum regime, it was used as a place to rehabilitate criminals, who were also used to defend the island. Horse cart paths and wooden, thatch roofed motels were also constructed during this time. Most of this infrastructure has been destroyed by weather and decades of war.
Today there are new bamboo guest houses on the main beach, visited by Cambodian and foreign tourists. In addition, fishermen and their families live on the island, occupying other beaches around the shoreline.