The Piper’s Hole is at the north east of these cairns.
Under the cliffs of Peninnis Head on St Mary’s there is a cavern, termed the Piper’s Hole, which extends a long distance under ground, and is absurdly said to communicate with another cave of the same title, the entrance to which is in the island of Tresco. This legend would make the length of the cavern at least four miles; and the inhabitants of the locality tell you of dogs let in at the one entrance coming out, after a time, at the other with most of their hair off, so narrow are some parts of the cave. So there is a tradition in Scotland of a man getting through a similar cave, but paying the penalty in the loss of all his skin.
From ‘Rambles in Western Cornwall’ by J O Halliwell-Phillipps (1861).