Two months ago, Reuters photographer Lucas Jackson was invited to the 2011 Applied Physics Laboratory Ice Station, a temporary camp built out of plywood on Arctic sea ice. Far north of Prudhoe Bay, Alaska, the camp housed a couple dozen members of the British, Canadian, and U.S. navies and employees of the Applied Physics Laboratory. Jackson spent two days at the camp, watching its residents conduct tests on underwater and under-ice communications and sonar technologies. He kept his camera equipment warm and functional with chemical hand warmers whenever possible. Collected here are some chilly images from Jackson's trip to the far north last March. Cables for sonar equipment lead into a hole that has been cut through the Arctic ice at the APLIS camp north of Prudhoe Bay, Alaska, on March 18, 2011. The new digital "Deep Siren" tactical messaging system built by Raytheon Co could revolutionize how military commanders stay in touch with submarines all over the world, allowing them to alert a submarine about an enemy ship on the surface or a new mission, without it needing to surface to periscope level, or 60 feet, where it could be detected by potential enemies. Applied Physics Laboratory Ice Station (APLIS) employee Hector Castillo, near the 2011 APLS camp north of Prudhoe Bay, Alaska. A congressional delegation and the Secretary of the Navy walk around the Seawolf class submarine USS Connecticut after the boat surfaced through through Arctic sea ice.