The Derwent is a river in Tasmania, Australia. The river rises in the state's Central Highlands and descends more than 700 metres (2,300 ft) over 200 kilometres (120 mi), flowing through Hobart, the state's capital city, before emptying into Storm Bay and flowing into the Tasman Sea. The Derwent River valley was inhabited by the Mouheneener people for at least 8,000 years before British settlement. Evidence of their occupation is found in many middens along the banks of the river. When first explored by Europeans, the lower parts of the picturesque valley were clad in thick she-oak forests, remnants of which remain in various parts of the lower foreshore. Agriculture, forestry, hydropower generation and fish hatcheries dominate catchment land use. The Derwent is also an important source of water for irrigation and water supply. Most of Hobart's water supply is taken from the lower Derwent River. Nearly 40% of Tasmania's population lives around the estuary's margins and the Derwent is widely used for recreation, boating, recreational fishing, marine transportation and industry. It was named after the River Derwent, Cumbria, by British Commodore John Hayes who explored it in 1793. The name is Brythonic Celtic for "valley thick with oaks". John Hayes placed the name "Derwent River" only in the upper part of the river. Matthew Flinders placed the name on all of the river. There was a thriving whaling industry until the 1840s when the industry rapidly declined due to over-exploitation. href='https://en.wikipedia.org/wiki/River_Derwent_(Tasmania)