Fell Beck is a stream near the foot of Ingleborough, in the Yorkshire Dales National Park.

It is notable for running into Gaping Gill, the second-largest natural cave shaft in the UK (after Titan).

[1] As it falls down the shaft for 110 metres it is the tallest unbroken waterfall in the UK.

[2] At times it is blocked off by a temporary dam to allow members of the public to descend the Gaping Gill shaft on a winch.

This was confirmed by cave divers in 1983, and by fluorescent dye tests many years before.