Hidra is the largest island in Agder county, Norway. The 20.8-square-kilometre (8.0 sq mi) island lies within Flekkefjord Municipality, south of the mainland coast, separated from it by the 350-metre (1,150 ft) wide Hidrasund strait and the Listafjorden. As of 2015, the island had about 500 residents, mostly living on the west side in Kirkehavn, where Hidra Church is located. Rasvåg is another main village, located on the south side of the island. In 2007, the Norwegian government studied the possibility of constructing an undersea tunnel to connect the island to the mainland without the use of a ferry; however, the project was deemed too costly relative to its benefits.