Torside Reservoir is a large freshwater lake nestled in Derbyshire, England, forming part of the Longdendale Valley chain of reservoirs in the Peak District. Covering approximately 55 hectares with a mean depth of 10.3 metres and a total water volume of nearly 5.7 million cubic metres, it is classified as a large, generally shallow water body. Situated at an elevation of 196 metres above ordnance datum, the reservoir has a catchment area of nearly 5,911 hectares and a perimeter of roughly 5 kilometres. The water chemistry is characterised by low alkalinity (mean alkalinity of 93 µEq/l) and moderate conductivity (63 µS/cm), with a notably humic quality reflected in its mean colour reading of 85.8 mgPt/l — giving the water a characteristic peaty, tea-coloured tint typical of upland Pennine reservoirs fed by moorland drainage. The fetch distance of just over 2 kilometres means wind can build meaningful wave action across the open water, making conditions on the reservoir dynamic and variable depending on the season and prevailing weather.