About five miles north of Moffat on the A701 Edinburgh road, the ground drops away into a vast, bowl-shaped hollow 150 metres deep, enclosed by four hills. It's one of the sources of the River Annan. The Johnstone reivers, whom their enemies called "devils", hid stolen cattle here, which is where the name comes from.
There's a viewpoint lay-by on the A701, and the view down into the Tub is impressive from the road.