Azurro, sky-blue appears the basal glacier ice in a cave on a deep winter day. Alternating ice layers with more or less air bulbs included are the product of weather and glacier mechanics. While air bubble rich ice appears white, blue light penetrates predominantly the clearer ice. Inside the glacier cave, the sky-blue light dominates and amplifies features that tell a fascinating story of a century long interplay between ice, water, vapour and air as well as shears and stresses on top, inside and underneath a mountain glacier. More and more of these caves vanish in our warming mountains.