Portsmouth is a port city and unitary authority located in Hampshire, England. It is situated off the south coast of England in the Solent, primarily on Portsea Island. Due to this geography, it is the only city in England that is not located primarily on the mainland.
The city is positioned approximately 22 miles southeast of Southampton and 74 miles southwest of London. It forms part of the South Hampshire urban area alongside Gosport, Fareham, Havant, Eastleigh, and Southampton. With a recorded population of 208,100, Portsmouth holds the distinction of being the most densely populated city in the United Kingdom.