 Calder's Geo is a large geo that cuts into the western black volcanic cliffs of Esha Ness.To the north of the geo is a sea cave that has been measured at more than one and a half times the size of "Frozen Deep", a chamber in Reservoir Hole under Cheddar Gorge in Somerset, potentially making it the largest natural chamber in Britain.There are numerous blowholes in the vicinity, notably the Holes of Scraada in a cleft where the sea appears about 300 yards from the cliff line on the west coast.