Welland Ship Canal, 27.6 mi (44.4 km) long, SE Ont., Canada, connecting Lake Ontario with Lake Erie and bypassing Niagara Falls. Built between 1914 and 1932 by Canada to replace a canal opened in 1829, it can accommodate (minimum depth 27 ft/8 m) the largest lake ships. Its eight locks overcome a 326-ft (99-m) difference in level between the lakes. The Lake Ontario entrance is near Port Dalhousie; the Lake Erie entrance is at Port Colborne. It is part of the St. Lawrence Seaway system.