Furness (/ˈfɜːrnəs/ FUR-nəs) is a peninsula and region of Cumbria in northwestern England. Together with the Cartmel Peninsula it forms North Lonsdale, historically an exclave of Lancashire.

The Furness Peninsula, also known as Low Furness, is an area of villages, agricultural land and low-lying moorland, with the industrial town of Barrow at its head. The peninsula is bordered by the estuaries of the River Duddon to the west and the River Leven in Morecambe Bay to the east. The wider region of Furness consists of the peninsula and the area known as High Furness, which is a relatively mountainous and sparsely populated part of England, extending inland into the Lake District and containing the Furness Fells.[1] The inland boundary of the region is formed by the rivers Leven, Brathay and Duddon, and the lake of Windermere. Off the southern tip of Furness is Walney Island, 11 miles (18 km) long, as well as several smaller islands.

The Borough of Barrow-in-Furness, which developed when the Furness iron industry flourished in the 19th century, is the region's largest settlement, with a population of over 91,000.[2] The remainder of Furness is predominantly rural, with Ulverston the only other settlement with more than 10,000 people. Much of High Furness consists of moorland, mountain or woodland environments.