Bastøy Prison is a low-security, male-only prison on Bastøy Island, Norway, located in the Horten municipality about 75 km south of Oslo. The prison is on a 2.6 km2 island and hosts 115 inmates making it the largest low-security prison in Norway. Arne Kvernvik-Nilsen, governor of the prison, leads a staff of 69 prison employees. Of this staff, only 5 employees remain on the island overnight. The prison is about one hour commuting distance from Oslo.

is a municipality in Vestfold county, Norway. It is located in the traditional district of Jarlsberg. The administrative centre of the municipality is the town of Horten. Other population centers in Horten Municipality include the town of Åsgårdstrand and the villages of Nykirke, Skoppum, and Borre. The municipality is located on a peninsula along the Ytre Oslofjord.