Lock 21Ontario

Dive site characteristics

Types Structure dive Drift dive
Conditions Visibility very restricted or null
Providers Parking Swimming Picnic tables W.C. Bathroom
Planning Rescue in case of emergency Weather conditionsFerries scheduleRoad conditionsRoad maps

Diving notes

Note: these pictures (of the lock’s front) have been taken on august 1st, 2003. There was a strong current!. Later, we learned that the Cornwall dam has been opened in order to massively produce electricity due to electric power fault in the American East area and Ontario.

It is important to take good reference point with the compass before diving. The visibility is sometime poor. The return has to be done in the right direction! The essential thing to remember is if you go against the current, the exit is on your right while with the current, the exit is on your left.

Classical entry methods

The diver make his entry from the point A as shown on the diagram above, the diver moves toward point C. Depending on the water current, it is better to follow the hashed line toward the point C. Near the shore make a backup walk and then make your swim as diagonaly as possible...the current will bring you to the buoy. This way will save you energy. Too many divers find themselves drifting away to the left (while facing the river) in the middle where the current is stronger.

If you decide to swim in straight direction toward the buoy, be sure to take your bearings and not to drift in the middle where is current is much stronger (as shown on the picture below).

The simplest, if you maintain that bearing, is to get toward the buoy, the air consumption underwater is variable to each individual but not much. You will be 4 to 6 feet deep and not breathless once arrived at the buoy.

At the buoy, there is a line (blue line on the diagram) going down the slope of the underwater terrain which will lead you toward the structure. Once arrived at what was a boardwalk, you will be 30’ deep (10m). You may go deeper at 60’ (20m) within the lock itself or continue your visit to the end of the lock by crossing to the other side and drift along with the current. Don’t forget you will have to come back, watch your air and fully respect the rule of thirds.

The idea is to start the dive differently. Let’s say you are at the buoy, you should descend along the line leading toward the beginning of the structure. The alternative method suppose the same approach except you start downstream from the buoy. The water current is about the same during the descent. From the point A (see the diagram) you move toward point C. You take your bearings with the little island (see picture #1). You walk as much as possible until the level of water is about at your knees for about 50 feet (15m) from the shore. You put your fins on. Again take your bearings. From that imaginary line you turn right by about 15 up to 25 degrees. Underwater follow that bearings. While diving againt the water current, grasp the bottom if needed. By maintaining your bearings, you should find yourself at the East end of the structure on the North wall (or at the 3/4 or at the half of it).

Descend inside the structure down to the bottom at about 60 feet deep. You will then be protected from the water current. You only have to follow the North wall toward West direction. You only have to ascend up to the boardwalk (like in the first method at the end of the line). This method is less energy consuming. The rest of the dive may be done as in the first method. You may take the same route on your way back. The only problem is the fact that no line can guide you for the entry or exit.

Other notes regarding the site

All the doors are closed except the second one from the South. Large gears may be seen from the West side. Following the Central wall will allow a drift dive. If you dive inside the the structure between the North wall, the lock’s doors and the Central wall, you may see all sort of garbages such as bicycles, showels, tires, etc.

At the end of the wall, you may also go to the North wall for the end of your dive. With enough air, you may observe at about 40’ deep the electricity poles which are still there from the Lost Villages.

The strong current is a menace on the entire dive site except the inner part of the structure. Be careful to lines, marine plants, the lock itself or other floating garbages which may be caught in your equipment. A compass is a must. A lamp is also a must if visibility is poor due to steady heavy rains during the previous days of your dive or high level of water.

Note: directions are accurate as possible. It is recommended to go with someone who knows the site. You may consult the guide from Save Ontario Shipwreck. You can also examine the old 1900 map modified (the current land is in green, the original waters are in blue and the white area has been immersed).

Source: Lost Villages Historical Society

On the picture, you can see the channel and the lock.

Entry points

Note: directions are accurate as possible. It is recommended to go with someone who knows the site.

  Depth   Site  Characteristics
To display on Google map, click on the link
120mLock 21 Descent along the line of the buoy which leads to the 30′ deep structure. The inner lock may reach 60′ deep. Watch your air constantly (rule of thirds) and the current which may get strong sometimes. The usual traject is to follow the transversal axis North-South and the promenade (West-East). This is not a dive for beginner. Visibility may change during season as well as current which mostly vary with rain conditions and the opening of the Cornwall power dam.
2?DamSheik Island dam. Informations to come.
330′Cimetière de barges
Barges cimetery 
Remains of 3 barges can be found, largely deteriorated at about 30′ deep. Visibility is very low. On the South side, there is a rope leading to the next site (Dread) at about 150′ at the South.
450′Dread Another damaged barge still having some equipment such as anchors and cabestan. The rope on the North side brings you back to the cemetery, the one on the South to the other site (Belly Dumper) at 400′ on the South-East.
580′Belly Dumper The barge is directly under the buoy. It is a wooden barge sitting on its side. It was used during the St.Lawrence Seaway construction. You will go around very quickly.
630′Quai du parc
Park wharf 
It is the old wharf. A dive flag is recommended as everywhere in Ontario.
730-65′Swing bridgeJust West of Milles Roches Power House. Only old stone piliars remains.
835-75′Power House Boat access. Follow the buoy line down to the 1st level at 30′. You may go down to the 2nd level at 55′ and then to the 3rd level at 75′.
960′Control damAccess by boat, on the East side of the Power House.
1075′Lock 20 Dive for expert only. Located à about 1km West of Cornwall dam (Moose Saunders Power Dam).

Driving directions

From highway 401, take exit 778 toward Long Sault. Take the South direction on Moulinette Road up to road 2 (also known as King’s Highway).

To get to Lock 21

Continue heading South direction on Moulinette Road crossing road 2 toward to Long Sault Parkway. You will have to stop and pay your entry fee (3.25 CAN$ per person; summer 2003). It is free the rest of the year. Follow the route up to the McDonnell Island (2nd island).

After driven half way of the island take then the 2nd gravel road and follow toward West direction. There is a brown pavilion (yellow square on the diagram) where informations are available about the dive site and an historic tour relating the story of the Lost Villages after the construction of the St.Lawrence Seaway. The Lock is located on the South side of the island on the St.Lawrence lake (not the St.Lawrence River which is located on the other side of the islands on the American side of the border). You may park your vehicule near the shore unless indicated. Please take note that CAN-US border is located at about 100 feet from the shore (30m).

To get to other sites

From highway 401, take exit 778 toward Long Sault. Take the South direction on Moulinette Road. Turn left on road 2 or Vincent Massey Drive. Follow the route 4.8km, heading East (passed the Lost Villages Museum) up to Guindon Park (take the West entry on the map).

Diver’s services

Providers Address Phone Services
Long Sault Parkway  County Road 2,
800 437-2233
613 543-4328
site access to lock 21
Ron’s Scuba Shop 13, 11th Street West,
613 933-1362 air, rentals,

© Copyright 1999-2016, Michel Robitaille. All rights reserved.