Portsmouth Harbour is a large natural harbour in Hampshire, England. Geographically it is a ria: formerly it was the valley of a stream flowing from Portsdown into the Solent. The city of Portsmouth lies to the east on Portsea Island, and Gosport to the west on the mainland. At its north end is Portchester Castle, of Roman origin and the first fortress built to protect the harbour.
Location: Clarence Esplanade, Portsmouth, Southsea, UK