How deep are the largest caves?

That's not an easy or obvious question to answer.

The world's deepest cave is Voronya or Krubera Cave, in the Urals I think? but it's not ever so long. Caves like that plunge steeply via many shafts linked byrelatively short horizontal passages.

The world's longest cave is the Flint Ridge Cave/ Mammoth Cave system, linking severals other caves too with a total of somewhere near 400 miles of passages; but I don't think its vertical range (as cave depths are oftenmore accurately described) is ever so great.

Incidentqally its name has nothing to with Pleistocene animals. "Mammoth" was the adjective for the large passages near its main entrance. (ref: Wikipedia)

In the UK, Ogod Ffynon Ddu, in South Wales, has a VR of just over 1000feet in its 28 miles of passages; I think the Three Coutnies System in NW England beats it indepth and length but it's not easy tryingto find this sort of information thanks to the internet!