Print article The scientists prepped for their descent into the maw of the Greenland ice sheet by drilling deep into the ice. They created two intersecting holes into the bed of a now frozen-over ice river, running a rope through them in the shape of a V to anchor their lines. It would be more than strong enough to carry their weight, but they drilled a second anchor as well - just in case. Then Matt Covington, a geologist and cave explorer who has spent more than a year of his life beneath the ground, was ready. He began to lower himself into the vertical cavern that, in the summer, fills with the chaos of a waterfall - a moulin. The sharp crampons on his boots gripped the ice. The fact that it was October now made the moulin a little safer, but Covington could still hear running water somewhere.