In this Saturday, March 22, 2014 photo provided by the U.S. Navy, sailors aboard the Virginia-class attack submarine USS New Mexico tie mooring lines after the submarine surfaces through the arctic ice at Ice Camp Nautilus, north of Alaska. Cracks in polar sea ice are prompting the Navy to break down the camp that provided support for an exercise involving submarines. The Navy says in a release Monday, March 24, 2014, that the commander of submarine forces ordered an early end to Ice Camp Nautilus because shifts in winds created instabilities in ice floes. (AP Photo/U.S. Navy, Joshua Davies)