Ingleborough, Yorkshire Dales karst: limestone pavements in horizontal limestone dissected by rundkarren on the eastern benches of the Yorkshire Dales (Photo: Tony Waltham)

White Scar Cave, Yorkshire Dales, UK: a classic keyhole passage with a pre-Anglian phreatic tube that was drained and entrenched in response to glacial deepening of the adjacent dale (Photo: Tony Waltham)

Ogof Ffynnon Ddu (Cave of the Black Spring), South Wales, UK: The Traverses (Photo: Jerry Wooldridge)

Peak Cavern, Derbyshire Peak District, UK: Mud crawl (Photo: Jerry Wooldridge)

Gaping Gill, Yorkshire Dales, UK: Fell Beck cascading into the Main Shaft (Photo: Jerry Wooldridge)

Castelletto di Mezzo Cave – Brenta Dolomites (Trento, Italy): ice plug inside a karstic cave (Photo: Cesare Mangiagalli)

Ventina Glacier – Val Malenco (Sondrio, Italy): the ice caves of this small glacier are doomed to disappear in a relatively short period due to global warming (Photo: Cesare Mangiagalli)

Ventina Glacier – Val Malenco (Sondrio, Italy): descending the entrance pit of a moulin (Photo: Cesare Mangiagalli)