The Welland Canal runs 43.4 km from Port Colborne, Ontario on Lake Erie to Port Weller, Ontario on Lake Ontario. It allows ships to avoid Niagara Falls by traversing the Niagara Escarpment. About 40 million tonnes of cargo passes through the canal annually. It also provides water for industry and a small amount of electricity.

The Port Weller end of the canal is 99.5m lower than the Port Colborne end. There are eight locks, each 24m by 234m. The canal is 9m deep.

The current canal, the fourth, was built between 1913 and 1932. The first canal, built by William Merritt, was completed in 1833.