The Mer de Glace in Chamonix, November 86: every summer the meltwater that runs on the surface of the glacier flows into a huge crevasse called "a mill". In 1897, Joseph VALLOT had explored it to a depth of 60m, a lake had prevented him from going any further. Since then no one had descended into this well. In the fall, a multidisciplinary team made up of mountaineers including Jean Marc BOIVIN, speleologists and scientists descending into the crevasse... Superb images and live comments in a temperature of 0° and a humidity of 100%. The team reached 110m deep under the ice, a world first in glacier exploration. Jean marc BOIVIN seems delighted with his first speleological exploration. With the participation of Serge AVIOTTE, Jean Michel ASSELIN, Jean Marc BOIVIN, Janot LAMBERTON, Pierrot PILLET, Louis REYNAUD, Jean Luc RIGAUD and Denis TERMIER.