Who discovered limestone caves?

Open caves have been known since time immemorial, obviously - Palaeolithic people used suitable local caves for shelter.

Serious exploration of caves started in the 19th Century, although a few hardy souls ventured into caves long before that and wrote what to us are rather lurid accounts of bottomless abysses and endless winding passages.

For some decades the early explorers concentrated on caves naturally already open but now, most "new" caves in the UK, Europe and the more accessible US caving areas are only discovered by "digging" - clearing natural chokes of glacial till or collapses that hide likely entrances. It's necessary to understand caves and karst processes, and basic geology generally, to be reasonably sure of finding a cave in this way.