Recorded in many spellings including Brownsea, Brownsie, Brownsey, Browncey, Bransey, Bronsey, and probably others, this is an English surname. It is locational and almost certainly from Brownsea Island which guards the entrance to the famous Poole Harbour in the county of Dorset. As to why the place should be called "brown sea" is unclear, but it may be owing to the severe currents at the harbour entrance which chirn up the sea bringing up the silt. The island itself has at various times had a large population, but at other times and on the whim of the owners has been reduced to only a few. Locational surnames are in any case usually from names. That is to say names given to people after they left their original homes to move somewhere else. This surname is quite well recorded in the various counties which surround Poole Harbour and examples taken from surviving church registers include Philobeth Browncey at Thorncombe near Axminster, Dorset, on November 15th 1572, and William Brownsie of North Curry, Somerset, on December 23rd 1583, Jone Brownsey at Langton Matravers, Dorset on October 26th 1679, and Peter Brownsea at the same place, on July 11th 1722.