Blockade of Boats, Ste. Saint Marie, Michigan. ca. 1900. The city is the site of the Soo Locks, which lets ships travel between Lake Superior and the lower Great Lakes. Although the locks are not as busy as in past years, a considerable amount of domestic and foreign commerce passes through them. People come from around the world to view close up the ships passing through the locks. The largest ships are 1,000 feet (300 m) long by 105 feet (32 m) wide. These are domestic carriers (called lakers) that are too large to transit the Welland Canal around Niagara Falls and thus are land-locked. Foreign ships (termed salties) are smaller.