Bournemouth is about 94 miles (151 km) southwest of London.[54] The borough borders the neighbouring boroughs of Poole and Christchurch to the west and east respectively and the East Dorset District to the north. Poole Bay lies to the South.[55][56] The River Stour forms a natural boundary to the north and east, terminating at Christchurch Harbour;[56][57] while the River Bourne rises in Poole and flows through the middle of Bournemouth town centre, into the English Channel.[58] The towns of Poole, Bournemouth and Christchurch form the South East Dorset conurbation with a combined population of over 400,000. Bournemouth is both a retail and commercial centre.[59] Areas within Bournemouth include: Boscombe, Kinson, Southbourne, Springbourne, Throop, Westbourne, Winton and Pokesdown.