Martin Critchley shot this lovely ice cave footage, which proved so popular he released an extended cut.
The otherworldly caves prove difficult to describe:
I take time to soak in my surroundings, a crystal grotto straight out of a Russian fairy story. Huge scalloped shaped walls of ice arch high over my head, sculpted by the passage of a now frozen river. Most of the smooth scallops end in a tiny pimple, a drop of water literally frozen in time. The colours – white, through deep turquoise, petrol blue, charcoal grey and inky black – are breathtaking. I stare intently into the translucent ice, seeing strange filaments the thickness of a human hair, specks of black volcanic grit and myriad clusters of air bubbles, trapped eons ago. I learn to read its coded message: stripes of subtly different coloured layers represent varying periods of snowfall over many centuries. Whiter layers tell us that the ice formed when the weather was very cold, because air was trapped within the snow making it more reflective. Conversely, layers that are darker or bluer in colour were created by snowfall in warmer or wet conditions when little air was trapped. I spy smooth pebbles and small boulders stuck fast in the ice as an insect in amber, and in places it is striated, testament to the relentless power of this glacier which is slowly grinding its way through the valley.
Read the rest here.
Bonus video: 13 more hypnotic minutes as ice and geysers collide: