Climbers captured spectacular pictures of ice appearing to glow blue as they descended 5,280ft into a glacier in Alaska.
American glacier trekking guide Jared Carlson snapped the eerie pictures a quarter of a mile into the Mendenhall Glacier, in Juneau. The 36-year-old was joined by fellow climber Jason Nelson, 37, as the pair explored the moulin, which is a circular, vertical well-like shaft within a glacier.
Jared, of Spokane, Washington, said: "Moulins can be incredibly intimidating. Picture a vertical shaft in the ice, 40 stories deep, with a huge river of water falling into it, which could not be any colder unless it was ice.The sound of the falling water is deafeningly loud and the spray from the falling water spreads out the deeper you go, and it gets continually darker.Add to this the fact that your life is entirely and wholly dependent on your technical competence, with absolutely zero margin for error - if you screw up and fall, you will die. Combine all of these factors and you have an incredibly intimidating, yet astonishing, indescribably beautiful environment that is unlike anything else on earth."