Blackbeck Tarn is a fine glacial tarn above the head of the Buttermere valley. Its outflow, to the north-west, drops through a cleft between Haystacks and Green Crag to tumble nearly 1000 feet down to Warnscale Bottom and thence into Buttermere.

From Blackbeck, fine views can be had of Buttermere (and Crummock Water in the distance) and of Great Gable to the south. The shores are a mix of rocky outcrops and grassy patches clad with heather and bracken.

Access is by well-trodden footpaths that are more often used to reach Haystacks, the final resting place of Alfred Wainwright.