Rat Hole is one of the entrances to the Gaping Gill cave system, located in the north bank of Fell Beck upstream of Gaping Gill Main Shaft. A small, awkward, tube-like passage descends into a stream passage, and hence to a shaft into Gaping Gill Main Chamber. The sharp and loose nature of the rock, and the quantity of water prevented full exploration for over 80 years, but the current route is described in one guide book as a technical and exhilarating adventure. It lies within the designated Ingleborough Site of Special Scientific Interest.