Portsmouth is a port city and unitary authority in Hampshire, England. Most of Portsmouth is located on Portsea Island, off the south coast of England in the Solent, making Portsmouth the only city in England not located primarily on the mainland. The city is located 22 miles south-east of Southampton, 50 miles west of Brighton and Hove and 74 miles south-west of London. With a population last recorded at 208,100, it is the most densely-populated city in the United Kingdom.