Alcock Tarn rests on a shelf at a height of 360 m (1,180 ft) on the lower slopes of Heron Pike in the Lake District's Eastern Fells area. Originally called Butter Crags Tarn, it was enlarged and deepened by its owner, Mr Alcock, in the 19th century to create a trout lake. Fishing for the small brown trout that proliferate in the tarn is permitted. Also popular is picnicking on the tarn's grassy banks while enjoying the spectacular with views out over Rydal and Grasmere to the Central Fells. The terrain on a 5.3 km (3.3 mi) circular walk from the Grasmere National Trust shop to Alcock Tarn is fairly steep in parts, so it's often possible to enjoy solitude away from the tourist crowds here.