The Welland Canal crosses the NIAGARA PENINSULA of southern Ontario. Port Weller is on the Lake Ontario side. PORT COLBORNE is on the Lake Erie side. Over the canal's 43.5 kilometres length it has to raise or lower boats 99.4 metres - the difference in elevation between the two lakes. The canal bypasses NIAGARA FALLS and the turbulent NIAGARA RIVER.

The canal has seven lift locks (each raises or lowers a ship 14.2 metres) and one guard lock. Vehicles and trains cross the canal by 11 lift-bridges, three tunnels, and one high-level bridge. In an average year, about 3300 ships pass through the canal, about 900 of which are ocean-going. It takes a ship about 11 hours to go through the canal.

The first Welland Canal opened in 1829. It has been rebuilt and expanded several times since. During the 1950s it was improved when it became part of the ST LAWRENCE SEAWAY. The most recent improvement was made in the early 1970s when a new channel was built to bypass the city of WELLAND.