Crows Nest Pass: Canadian Rockies: Clear Ice Makes Explorers Feel They Are Flying
With apologies for the Daily Fail link:
Link 1: Booming Ice Chasm: Underground chamber beneath Rocky Mountains has giant ice slides that never melt | Mail Online
Edit: Explorers' blog:
However, although the water makes people feel like they're flying, one slip can send climbers hurtling down the frozen water slide slamming into the wall below.
Link 2: Crows Nest Pass: Canadian Rockies: Francois-Xavier De Ruydts: Blog