The water temperature underground, in the ancient Cheshire Basin reservoir, is about 100C (212F).

BBC: Newcastle borehole project

Much of Dublin's early history is as murky as the peaty basin where the River Liffey joined the now-underground River Poddle, near the site of what is today the Dublin Castle gardens.

BBC: Dublin's Viking heritage

The agreement calls for the water system to be treated as a single complex ecosystem made up of countless tributaries, underground aquifers and smaller lakes all held in the Great Lakes basin.

NPR: Governors Meet on Access to Great Lakes