The north-eastern face of Mardale Ill Bell forms the craggy backdrop to Blea Water. This perfect corrie tarn is the deepest in the Lake District at 207 ft. Its outflow feeds Haweswater, joining with that of a second tarn, Small Water. Between the two, Mardale Ill Bell throws out the rocky spur of Piot Crag. Two tiers of crag drop down to the confluence at Mardale Waters.