www.o2togo.ca · Operator
Dive site access route, rope entry, and park-adjacent logistics.
Dive Spot Guide•
Lock 21
Lock 21 is a historic current dive on a submerged canal lock.
Scuba DivingShoreAdvanced
RiverWreck
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Shore access from Long Sault Parkway, with a swim to the buoy and a current-heavy route best suited to experienced scuba divers.
About Lock 21
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.
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Research Estimate At Lock 21
Conservative baseline from public research. No community dives logged yet.
VisibilityVisibility: 3m
AccessModerate entry effort
FacilitiesBasic facilities
Crowd / PopularityQuite busy
CurrentStrong current
Where Is Lock 21?
This spotNearby spots
Community sourced coordinates.
Lock 21 Planning Details
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.
Safety & Access At Lock 21
Hazards, restrictions, and access requirements.
Key Hazards
Low visibilityStrong current
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.
Local Intel For Lock 21
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.
Lock 21 Dive Conditions Planner
Use the planner to scan this week, inspect today in local time, and understand how exposure shapes conditions at Lock 21.
Current Snapshot
No data
🌥️Variable
Sunrise
No data
Time
No data
Sunset
No data
Surface / Entry
Wind No data · Tide No data
Sea State
Swell No data · Period unavailable
Visibility Outlook
Rain chance No data
Wind
No data
Swell
No data
Exposure Profile at Lock 21
Directional shelter context for incoming swell.
Exposure Note
Hourly forecast data is not available yet.
Recent Logged Visits At Lock 21
Community dive logs and visit reports for this site.
No Dive Logs Yet
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Dive Spot Log Averages At Lock 21
Average conditions based on logged dives & visits.
Conditions
Avg. Visibility3m
Activity
No dive activity logged yet.
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Lock 21 Guide - Frequently Asked Questions
Planning answers for access, conditions, timing, and site logistics.
Lock 21 Guide - Sources and Updates
Last Updated
Research Sources
www.seawayvalleydivers.com · Community Blog
Published Oct 25, 2024Crowding, current, and route-management notes from local divers.
www.stlawrenceparks.com · Official Tourism
Park page with Lock 21 overview, access, and nearby facilities.
www.thescubanews.com · Dive Directory
Published Jun 28, 2023Current, visibility, and depth notes for the lock structure.
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