Selsey is a seaside town and civil parish, about eight miles (12 km) south of Chichester, in the Chichester District of West Sussex, within the historic county of Sussex, England. Selsey lies at the southernmost point of the Manhood Peninsula, almost cut off from mainland Sussex by the sea. It is bounded to the west by Bracklesham Bay, to the north by Broad Rife (rife being the local word for stream or creek), to the east by Pagham Harbour and terminates in the south at Selsey Bill. There are significant rock formations beneath the sea off both of its coasts, named the Owers rocks and Mixon rocks. Coastal erosion has been an ever present problem for Selsey.
There is only one road (the B2145) in and out of the town, which at a point known as "the ferry", crosses a bridge over the water inlet at Pagham Harbour. At one time Selsey was inaccessible at flood tide, and a boat was stationed at the ferry to take horses and passengers to and from Sidlesham.