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Brave: Hulya Vassail climbs the sheer, treacherous walls of a moulin ice cave, formed by meltwater on Chamonix's Mer de Glace glacier
Treacherous: The walls of the cave are made entirely from slippery ice, and climbers face a 20m plummet to jagged ice below if their ropes fail to hold them
Courage: Alexandre Buisse clung to supports screwed directly into the walls of ice to capture these spectacular images of his friends climbing in the caves
Look! No hands! Ms Vassail reaches the narrow mouth of the crevasse - and heartstoppingly lets go to allow the rope to take her entire weight at the top
Daunting: Giulia Monego faces the terrifying climb out of the crevasse
Daredevil: Ms Monego tackles the daunting ascent from the icy cave, which Mr Buisse said was about 20m deep, and three by six metres wide
Tools for the job: Wielding an ice axe and with her boots equipped with crampons, Ms Monego makes her way up the steep walls
Dark: These pictures show Ms Monego as she climbs from a second, deeper, narrower cave
Seasonal: here is only a short window of time in November and December each year when the caves can be climbed
