Question: Furness Fells is flanked by which Cumbria lake?
Context: Thwaites is a small village near Duddon Valley and on the edge of the Duddon Estuary in the Lake District National Park in Cumbria, England.  The River Duddon flows through the valley, rising in the mountains between Eskdale and Langdale, before flowing into the Irish Sea near Broughton in Furness.  In its lower reaches it is bounded by the Furness Fells and Harter Fell. Finsthwaite is a small village in the South Lakeland District, in the county of Cumbria.  It is located near the Furness Fells and Windermere.  Finsthwaite has a place of worship, St Peter's Church, and a Bobbin Mill called Stott Park Bobbin Mill, now a working museum. Furness ( ) is an area of Cumbria in northwestern England.  Together with Cartmel it forms North Lonsdale, which was historically an exclave of Lancashire.  The region may be split into two areas: Low Furness and High Furness.  The former consists of the headland bounded on west by the Duddon estuary and on the east by Morecambe Bay, while the latter extends inland into the Lake District and contains the Furness Fells.  Off the southern tip of Low Furness is Walney Island, eighteen kilometers in length, as well as several smaller islands. The Furness Fells are those hills and mountains in the Furness region of Cumbria, England.  Historically part of Lancashire, the Furness Fells or High Furness is the name given to the upland part of Furness, that is, that part of Furness lying north of the line between Ulverston and Ireleth.  The hills lie largely within the English Lake District. The Duddon Valley is a valley in the Lake District National Park in Cumbria, England.  The River Duddon flows through the valley, rising in the mountains between Eskdale and Langdale, before flowing into the Irish Sea near Broughton in Furness.  In its lower reaches it is bounded by the Furness Fells and Harter Fell. Coniston Water in Cumbria is the third largest lake in the English Lake District.  It is five miles long by half a mile wide (8 km by 800 m), has a maximum depth of 184 feet (56 m), and covers an area of 1.89 sqmi .  The lake has an elevation of 143 feet (44 m) above sea level.  It drains to the sea via the River Crake. The Brathay is a river of north-west England.  Its name comes from Old Norse and means "broad river".  It rises at a point 1289 feet (393 m) above sea level near the Three Shire Stone at the highest point of Wrynose Pass (grid reference [ NY277028] ) in the Lake District.  Its catchment area includes the northern flanks of Wetherlam, Great Carrs and others of the Furness Fells, as well as a substantial area of the Langdale Fells. The Southern Fells are a group of hills in the English Lake District.  Including Scafell Pike, the highest peak in England, they occupy a broad area to the south of Great Langdale, Borrowdale and Wasdale.  High and rocky towards the centre of the Lake District, the Southern Fells progressively take on a moorland character toward the south west.  In the south east are the well known Furness Fells, their heavily quarried flanks rising above Coniston Water. The Old Man of Coniston is a fell in the Furness Fells in the English Lake District.  It is 2634 ft high, and lies to the west of the village of Coniston and the lake of the same name, Coniston Water.  The fell is sometimes known by the alternative name of Coniston Old Man, or simply The Old Man.  The mountain is popular with tourists and fell-walkers with a number of well-marked paths to the summit.  The mountain has also seen extensive slate mining activity for eight hundred years and the remains of abandoned mines and spoil tips are a significant feature of the north-east slopes.  There are also several flocks of sheep that are grazed on the mountain. Seathwaite Tarn is a reservoir in the Furness Fells within the English Lake District.  It is located to the south of Grey Friar and to the west of Brim Fell (on the ridge between The Old Man of Coniston and Swirl How) and north east of the village of Seathwaite on the east of the Duddon Valley.
Answer: Coniston Water