Elter Water is a small lake that lies half a mile (800 m) south-east of the village of Elterwater. Both are situated in the valley of Great Langdale in the English Lake District. The name Elterwater means either Lake of the Swan or Lake of Alder. Thomas Frederick Worrall painted a watercolour of the lake with Langdale Pikes in the background. This painting is hanging in the Bishop's House, Keswick.
The lake is 1030 yd (930 m) long and varies in width up to a maximum of 350 yd (320 m), covering an area of 0.06 mi2 (0.15 km2). It has a maximum depth of 20 ft (6.1 m) and an elevation above sea level of 187 ft (57 m). The River Brathay which provides outflow from Elter Water flows south to join Windermere, near Ambleside.
Navigation is prohibited on the lake.
" 'The lake frequented by swans', from ON 'elptr'/'alpt' 'swan', in the gen.[itive], sing.[ular] form with '-ar', and 'water', probably replacing ON 'vatn' 'lake'. Whooper swans still winter on the lake". (ON is Old Norse).