Dive site access route, rope entry, and park-adjacent logistics.
Lock 21 is a historic current dive on a submerged canal lock.
Lock 21 is a historic current dive on a submerged canal lock.
Lock 21 is a historic current-heavy scuba site on a submerged canal lock in the Long Sault area. Divers follow a shore-based swim to the upper structure, then work the lock walls and sheltered basin, where the flow eases but route control still matters. It suits experienced divers who are comfortable with line work and limited visibility.
Conservative baseline from public research. No community dives logged yet.
Depth range, seasonality, and planning context.
Reported Depth
9.1m - 19.8m
Depth Note
The upper structure sits around 30-40 ft, with the lock bottom around 60-65 ft; exact depth depends on the route line or wall chosen.
Best Season
summer
Typical Conditions
Strong river current, rope-assisted navigation, and limited visibility are common; the upper structure feels the current most, while the lock interior is calmer.
Hazards, restrictions, and access requirements.
Key Hazards
Safety Notes
Carry a dive light, plan for current, and keep a conservative exit plan for the return swim.
Access Restrictions
Parkway entry fee applies, and this is a shore-access dive rather than a boat-launch entry.
Legal Notes
Follow park access rules and check river conditions before entry; the site sits in park-managed access.
Community notes to help plan your visit.
Scuba Diving
Experienced divers can follow the rope to the upper structure and work the lock walls or basin; current control and line awareness matter most.
Freediving
Not a strong freedive target; the current and route management favor scuba with a planned line-based approach.
Snorkeling
A short snorkel swim may be used to reach the buoy, but the main site is current-heavy and better suited to scuba.
Community dive logs and visit reports for this site.
Average conditions based on logged dives & visits.
Planning answers for access, conditions, timing, and site logistics.
Last Updated
Research Sources
Dive site access route, rope entry, and park-adjacent logistics.
Crowding, current, and route-management notes from local divers.
Park page with Lock 21 overview, access, and nearby facilities.
Current, visibility, and depth notes for the lock structure.
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