What a trippy picture! Is this in one of the bergschrunds, or a crevasse, ...?!
This feature is called a moulin. When a crevasse begins to close up, water is routed towards the opening that remains. The friction between the falling meltwater and the ice walls creates enough heat to melt part of the wall. Eventually the crevasse closes completely except for the hole that is maintained by the large amount of meltwater falling down it. As we descended we could see closed cracks that looked like suture zones in the ice.
Right on- thanks for expanding my knowledge of how glaciers work!