Lock 21 is located at the upper entrance to the 11-mile-long Cornwall Canal, which was built to avoid the Great Sault Rapids. The lock is on the south side of the island on St. Lawrence Lake not on the St. Lawrence River. It was built in 1885/86 as part of a second canal system expansion, and it is 270 feet long between the gates, 45 feet wide, and has 14 feet clearance over the sill. The lock was operated by the Department of Railways and Canals until 1936, when it was taken over by the Department of Transport when the area was flooded to serve as the headwater for the Cornwall Hydro dam.
- A dive light is mandatory
- Be advised of a strong current::2-3 knots
- Lock Bottom is 60 feet, while upperwork is 40 feet
- On a good day, visibility is 8-12 feet
- Lines are available, placed by divers
Lock 21 is an exciting and one-of-a-kind dive that takes you back in time to a 19th century submerged Victorian canal lock on the St. Lawrence River.
The St. Lawrence Parks Commission manages the Parkway’s facilities. Picnic tables are available, as well as a snack bar, restrooms, a nature trail, and camping facilities.
YouTube Video Fishfinders 2015