From Cambridge University Caving Club - CUCC wiki
These were taken in Swildon's Hole, in the Mendips, on CUCC's first meet of the new academic year. The photographer was club flashmeister Peter Clifton, the only man I know capable of taking a photograph in a pitch black cave and making it come out overexposed.
Olly Madge contemplating Swildon's Sump 1
L-R: Anna Dugdale, Olly Madge, Dan Bower.
Anna, Olly and Dan again, with the sump pool in the background.
Olly, Anna and Dan inspecting some formations. (This looks to me like the bottom of the climb down from Barnes' Loop.)