Scuba Diving Excursions
Scuba diving excursions with
DECOSTOP Outdoor Centre
are designed to help certified divers explore local freshwater sites with confidence and purpose. These are not rushed outings. They are thoughtfully planned dives led by professionals who know the water, the conditions, and the history beneath the surface.
Our excursions are ideal for divers who want guidance, local insight, and a well-organized dive experience.
Guided Dives. Local Knowledge. Meaningful Experiences.
The St. Lawrence River offers some of the most unique freshwater diving in North America. From historic shipwrecks to submerged landmarks and river features, every site has a story and specific conditions that demand respect and preparation.
Our team plans each excursion with site selection, conditions, diver experience, and safety as top priorities. You arrive prepared, informed, and ready to enjoy the dive.
Diving with Respect and Awareness
We believe great diving experiences go hand in hand with environmental responsibility. Our excursions emphasize respectful interaction with underwater environments and historical sites. This approach helps preserve these locations for future divers and strengthens your connection to the places you explore.
What to Expect on a DECOSTOP Scuba Diving Excursion
Every excursion is carefully structured to support a safe and enjoyable dive.
- Site briefings that cover history, layout, depth, and conditions
- Clear dive plans and objectives
- Guidance tailored to the experience level of the group
- Emphasis on buoyancy control, awareness, and responsible diving
- Support before, during, and after the dive
Whether it is your first time diving a local wreck or a return visit to a favourite site, our goal is to help you get more from every dive.
Who These Excursions Are For
Our scuba diving excursions are well suited for:
Certified divers looking to explore local sites safely
Divers new to the St. Lawrence River
Students building experience after certification
Divers who value structure, guidance, and local expertise
Upcoming Dive Excursions
Plan Your Next Dive
If you are ready to explore local freshwater diving with experienced guidance, DECOSTOP Outdoor Centre is here to help you take the next step. If you are unsure whether an excursion is appropriate for your experience level, our team will help you decide.
LOCK 21 - Long Sault
Lock 21 is located in the Long Sault Provincial Park, managed by Parks of the St. Lawrence. This site offers a unique diving experience in a 2-3 knot current in the St. Lawrence River at a depth of 65 feet (20 metres).
You can visit an old flooded lock, the gates, various mechanisms that operated the lock, a rail trailer, and the foundations of the lockkeeper's cabin. In particular, invasive exotic species, such as the round goby, as well as bass, sunfish, perch, carp, walleye, St. Lawrence eels, crayfish, and spotted loaches, use this area to shelter from the current.
Located in a magnificent setting, this site offers diving in the St. Lawrence River current down to 70 feet. You can visit the two locks and the foundations of the lockkeeper's cabin. A multitude of fish use this area to shelter from the current.
This is a dive for advanced divers. Expect strong currents on the return trip.
LOCK 23
Lock 23 is a magnificent site on the St. Lawrence River, accessible from the shore and relatively close to Montreal. The depth is fairly shallow (50 feet maximum), but the strong current and poor visibility (10-15 feet) make it a site for advanced divers. However, visibility generally improves to 25 feet or more starting in September.
Lock 23 offers several structures to visit. The westernmost structure, the old Morrisburg Pump House, is located just in front of the town's new pump station, on the south wall of the old navigation canal. On the same wall, 100 metres to the east, is a hydropower station southwest of the Morrisburg church. Lock 23 is located 500 metres further east.
Among other things, you can see the structure in very good condition, the foundations of the lockkeeper's hut and the shore of Lock 23, where you can still see fences and tree stumps. Like most river dives, bass, walleye, carp and yellow perch are abundant here. It is also not uncommon to see large catfish in the corners of the lock.
Robert Gaskin Wreck
Just off Blockhouse Island, near Brockville, a buoy marks the location of this magnificent wreck.
The Robert Gaskin, a former 132-foot by 26-foot wooden three-masted sailing ship, lies perpendicular to the current. Its bow points towards the shore at a depth of 55 feet, and its stern at a depth of 69 feet. Several openings on both sides allow divers to easily swim through.
Despite its apparent proximity to shore (450 m), access is usually by boat. The current is generally weak and visibility is good. More experienced divers with sufficient air supply, or even two tanks, can reach Robert Gaskin from the riverbank.
MILLE ROCHES - Power House
The former Mille Roches hydroelectric power station offers a unique diving site. It is one of the region's underwater heritage jewels, which disappeared when the waters of the Cornwall Dam reservoir rose.
Accessible only by boat, this magnificent site allows divers to explore the various structures of the power station, which are still in very good condition. Although the walls and roof of the power station were removed before the flooding, most of the mechanisms and water turbines remain intact.
Depending on the season, the current will range from 2 to 3 knots, as long as you are not protected by the structure. Visibility will range from 15 to 20 feet if conditions are favourable. Several parts of the power station are sheltered from daylight, so a torch is essential to fully enjoy the visit. The site is also a good place to observe eels and catfish.
Eascliff Hall
The Eastcliffe Hall is a magnificent 343-foot-long wreck located in the St. Lawrence River about 3 km west of Upper Canada Village in Ontario. The wreck lies at a depth of up to 72 feet (22 metres) near the US border and the Seaway.
This dive is reserved for experienced divers who are accustomed to strong currents (3 to 6 knots) and who are skilled at navigating. It is a boat dive that absolutely requires the presence of a lookout to watch the boat, given the traffic and strong currents.
Scuba Diving Expeditions
Big Dives. Unforgettable Destinations.
DECOSTOP scuba diving expeditions are extended world-class dive adventures designed for divers who want to go beyond a single weekend or destination. From logistics and dive planning to local insight and safety oversight, every expedition is structured so you can focus on exploring extraordinary environments, building experience, and fully immersing yourself in the journey.
Philippines: Atlantis Dive Resort & Liveaboard
Diving with Atlantis Dive Resorts and Liveaboards, you’ll experience the Philippines’ premier dive destinations, in the heart of the Coral Triangle, with incredible marine biodiversity, all while enjoying a five-star experience.