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. 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, eighteen kilometers in length, as well as several smaller islands.
Barrow, which developed when Furness's iron industry flourished in the 19th century, dominates the region's human geography: the surrounding borough contains three quarters of the total population of 91,563. 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.
The name, which is first recorded in 1150 as Fuththernessa, is interpreted as "headland by the rump-shaped island," from Old Norse futh (genitive futhar), meaning rump, and nes, meaning headland. The island in question may be Piel Island, with the name originally referring to the headland immediately opposite (where Rampside is), before being extended to the entire region. Alternatively it could be Walney Island: though it little resembles a rump today, erosion could have altered its shape over time.
Furness's border follows the River Duddon up to Wrynose Pass, and then the Brathay until it flows into Windermere. The mere forms most of the eastern boundary, with the rest being made up of the Leven, from its source at Windermere's southern tip to its mouth at Morecombe Bay. In total Furness has an area of about 647 square kilometers.
The Furness Fells are formed of Ordovician volcanic rocks, and Silurian shales and slates to the south. They are cut through by Windermere, Coniston Water, and numerous valleys which drain into the Esk, the Duddon, and Morecambe Bay. The higher ground is rocky heathland, with frequent tarns, while the lower ground supports pasture and woodland. In the east there are two main chains of hills: one overlooking Windermere, with Latterbarrow (245m) as its highest point, and the other, which reaches 300m, overlooking Coniston Water. Between them is flat country and Esthwaite Water. West of Coniston Water is the highest range, the Coniston Fells, with the Coniston Old Man (803m) as its highest point (and historically the highest point in Lancashire). A lesser range extends from Torver to just north of Dalton, but south of that the landscape is flat; this area is also called Plain Furness. The low rolling hills of Low Furness are formed of glacial deposits, mainly boulder clay, above Triassic sandstone and Carboniferous limestone. There are large deposits of iron ore here, of very pure quality.