The Coast Guard Cutter Mackinaw, a 240-foot Icebreaker homeported in Cheboygan, Mich., passes through the Poe Lock, one of five locks that make up the Soo Locks in Northern Michigan, March 14, 2013. The Mackinaw was the first ship through the Poe Lock since it closed for annual maintenance in January. (U.S. Coast Guard photo by Coast Guard Academy Cadet Jonathan Young)