Question 1

Are there dive operators or facilities near Lock 20?

Accepted Answer

Local dive operators in the Cornwall, Ontario area provide guided dives, rental gear, and site orientation for the Cornwall Canal lock sites. On-site facilities at the parkway are basic, so bring your own gear setup and a buddy familiar with the site. Contact operators in advance to confirm current access and conditions.

Question 2

Do I need a permit or fee to access the Lock 20 dive site?

Accepted Answer

Access to the Long Sault Parkway area where Lock 20 is located is managed by the St. Lawrence Parks Commission. A seasonal vehicle entry fee applies during the operating season. No special dive permit is required beyond the parkway entry fee, but confirm current access rules with the Commission or a local dive operator.

Question 3

How strong is the current at Lock 20, and how should I plan for it?

Accepted Answer

Current at Lock 20 is variable and influenced by the upstream Cornwall hydroelectric barrage. It can range from mild to strong. Plan your dive around slack-water periods when possible, confirm current conditions with a local dive operator before entry, and always establish your exit points before descending.

Question 4

What fish and wildlife can I expect to see at Lock 20?

Accepted Answer

Lock 20 is a freshwater river site with species typical of the St. Lawrence system: smallmouth and largemouth bass, yellow perch, northern pike, and walleye are commonly present. There is no coral or tropical marine life, but the historic lock structures attract resident fish populations.

Question 5

What is the best time of year to dive Lock 20?

Accepted Answer

The practical dive season at Lock 20 runs from late spring through early fall, roughly May to October. Summer months offer the warmest water and most stable conditions. Spring brings colder water and potentially lower visibility from runoff. Confirm Long Sault Parkway seasonal access before planning a trip.

Question 6

What is the difficulty level for diving Lock 20?

Accepted Answer

Lock 20 is best approached at intermediate or above experience level. The primary challenges are variable river current, the site's proximity to the hydroelectric barrage, and the need for reliable navigation in freshwater with limited visibility. Newer divers should dive this site with an experienced guide.

Question 7

What kind of underwater structures can I explore at Lock 20?

Accepted Answer

Lock 20 features the submerged remains of a 270-foot stone lock chamber from the historic Cornwall Canal, alongside an older 200-foot lock and a weir structure. You can trace hand-cut limestone masonry walls, wooden gate and lock remnants, and the weir apron along the river bottom.

Question 8

Why was Lock 20 submerged, and when did this happen?

Accepted Answer

Lock 20 was part of the Cornwall Canal, which was inundated in 1958 when the St. Lawrence Seaway was constructed. The Seaway required deepening the channel to accommodate oceangoing vessels, which flooded much of the old canal system along with several nearby villages.

Lock 20

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