Subterranean waterfall

A subterranean waterfall, tierous waterfall, or underground waterfall is a waterfall located underground, usually in a cave or mine.

They are a common feature in cave systems where there are vertical or near vertical geological structures for the weathering process to exploit, and sufficient gradient between the sink and the rising.

[1][2] Notable examples include Ruby Falls, 44 metres (144 ft) high, in Chattanooga, Tennessee[3] and Gaping Gill in the Yorkshire Dales, UK with a fall of 98 metres (322 ft).

The highest known subterranean waterfall is in Vrtoglavica Cave in Slovenia, and is at least 400 metres (1,300 ft).

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