Ullswater is the second largest lake in the English Lake District, being approximately nine miles (14.5 kilometres) long and 0.75 miles (1,200 m) wide with a maximum depth of slightly more than 60 metres (197 ft).
Many regard Ullswater as the most beautiful of the English lakes: it has been compared to Lake Lucerne in Switzerland. It is a typical Lake District narrow "ribbon lake" formed after the last ice age when a glacier scooped out The Valley floor and when the glacier retreated, the deepened section filled with meltwater which became a lake. A total of three separate glaciers formed the lake. The surrounding mountains give Ullswater the shape of a stretched 'Z' with three distinct segments (or 'reaches') that wend their way through the surrounding hills.