Cattle Culvert is a shallow artificial reef located near Guindon Park in the Brockville and Thousand Islands region. This site features a stone-cut railroad culvert, historically used for cattle crossings, which now rests underwater. Accessible via a shore entry from Lakeview Beach, the site is suitable for beginners. Divers and snorkellers can explore the structure at depths ranging from 1 to 10 metres, with an average depth of 5 metres. Conditions are generally mild with visibility varying between 3 and 10 metres. Divers should be aware of potential entanglement hazards due to the nature of the submerged structure. Facilities including parking, toilets, and showers are available nearby.

Mille Roches Powerhouse is a submerged hydroelectric generating station located in Lake St. Lawrence. This artificial reef and wreck site features massive turbines and discharge tunnels that remain intact. The roof of the structure was removed, allowing for visibility of the machinery from the surface on clear days. Divers can explore the site at depths ranging from 5 to 17 metres, with an average depth of 12 metres. Access is by boat only, located 926 metres from the shore. Conditions include moderate currents and visibility between 15 and 30 metres. Hazards include boat traffic, deep water, and overhead environments. The site is suitable for intermediate divers and offers night diving opportunities.

Mille Roches Beach is the largest sand beach on the St. Lawrence River, providing a gentle shore entry for snorkelers. The site features a shallow bay with depths ranging from 1 to 5 metres, averaging 3 metres. Conditions are generally mild, though visibility varies between 1 and 3 metres. The area is suitable for beginners interested in observing local aquatic plants and the general kinds of temperate freshwater fish and invertebrates expected in this habitat. On-site facilities include parking, toilets, changing rooms, showers, and equipment rental.

Lock 21 is a submerged 19th-century Victorian lock located in the Brockville and Thousand Islands region of Canada. This site features massive stone walls and upper structures that remain visible just below the surface. Divers access the site from the shore, with the structure situated approximately 30 metres out. The depth ranges from 9 to 18 metres, with an average of 14 metres. Conditions include strong currents, low visibility of 3 metres, and cold water, making this an advanced dive. Facilities at the site include toilets and showers. Snorkellers can explore the upper structures near the surface.

Mc Laren Island is a shore-entry dive site located in the Brockville and Thousand Islands region of Canada. Divers can expect depths ranging from 3 to 8 metres, with the site situated approximately 50 metres from the shore. Conditions at this location are variable, with visibility typically between 4 and 15 metres. The site is subject to strong currents, making it suitable for intermediate divers. Water temperatures remain cold throughout the year, fluctuating between 4°C and 20°C, which necessitates the use of drysuits or thick wetsuits. Facilities available at the site include parking, showers, toilets, and access to boat charters.

The Lost Villages is a unique freshwater site where remnants of the original Highway 2 remain submerged in the St. Lawrence River. Divers can follow asphalt roads, yellow lines, and road signs that lead into the depths. The site is suited for intermediate divers due to moderate currents and potential entanglement hazards. Visibility is variable, ranging from 20 to 80 metres. The water temperature remains consistent throughout the depth profile with almost no thermoclines. Facilities at the site include parking, toilets, showers, changing rooms, a rinse station, air fills, a dive shop, and boat charter services. Snorkelling is possible but limited, with a rating of 2 out of 5.

Crysler Park Beach in the United States near Morrisburg is a designated swimming area suitable for beginner snorkelers. The site features a sandy bottom and depths ranging from 1 to 5 metres, with an average depth of 3 metres. Snorkellers can expect mild currents and visibility typically between 3 and 8 metres. Access is via a shore entry, and the site is equipped with parking, toilets, showers, changing rooms, and a cafe. Hazards at this location include boat traffic, cold water, and low visibility. A typical snorkel session lasts approximately 30 minutes.

Eastcliffe Hall is a freshwater shipwreck located 1200 metres offshore in the Brockville and Thousand Islands region. The wreck lies at depths between 6 and 30 metres, with an average depth of 18 metres. Divers must access the site by boat. Conditions include strong currents and visibility ranging from 5 to 10 metres. The wreck presents an overhead environment with potential entanglement hazards, requiring intermediate skill levels and proper equipment. Water temperatures remain consistent from the surface to the bottom during summer months. Guided tours and boat charters are available for those exploring the hull, and night diving is permitted.