Bournemouth is a coastal resort town in the Bournemouth, Christchurch and Poole unitary authority area, in the ceremonial county of Dorset, …Bournemouth is a coastal resort town in the Bournemouth, Christchurch and Poole unitary authority area, in the ceremonial county of Dorset, England. The 2021 census built-up area had a population of 196,455, making it the largest town in Dorset.