1 / 3   Two climbers make an incredible journey up a cylindrical ice cave – naturally carved out of a glacier. /VCG Photo

2 / 3   The tube-like cave, which has been gradually formed by melting water during the summer months, is around 50 meters deep. /VCG Photo

3 / 3   Photographer Mathis Dumas, together with champion climber Jeff Mercier, scaled the unique ice tunnel after Mathis stumbled across it while guiding clients over Mont Blanc. /VCG Photo