inlet of the Tasman Sea, extending northeast for about 35 miles (55 km) between Bruny Island (east) and the southeast coast of mainland Tasmania, Australia, to merge with the Derwent River estuary. Sighted in 1642 by the Dutch navigator Abel Tasman, it was surveyed in 1792 by the French admiral Bruni d'Entrecasteaux, who proved it to be a channel rather than a bay. It is known locally as The Channel. Its western shoreline, paralleled by the Channel and Huon highways, is interrupted by the large indentations of Port Esperance and the Huon River estuary. The channel is the southern approach to Hobart.