The Niagara II is a shipwreck and artificial reef located in Big Tub Harbour, Lake Huron. Resting at depths between 10 and 40 metres, this site is suited for intermediate divers with appropriate wreck certification. The wreck features an overhead environment that requires careful navigation. Divers should expect cold water temperatures, typically ranging from 4 to 7 degrees Celsius at depth, with significant thermoclines present. Visibility varies from 5 to 20 metres. Access is by boat only, and divers must remain aware of mild to strong currents. Due to the consistently cold conditions, a drysuit is strongly recommended for all dives.

The Caves in Big Tub Harbour feature dramatic limestone formations and an underwater tunnel accessible to both divers and snorkellers. Located within Fathom Five National Marine Park, this site offers depths ranging from 6 to 10 metres with an average of 8 metres. Conditions are characterised by consistently cold freshwater temperatures and visibility varying between 5 and 25 metres. Entry is typically by boat, though the site is also accessible from flat rock shelves. Due to the cold water and potential for boat traffic, this site is best suited for intermediate divers. The site provides a unique opportunity to explore geological cave structures in a freshwater environment.

Thomas Place is a shallow freshwater reef site located in Big Tub Harbour. With an average depth of one metre, it provides a controlled environment for beginner divers to build confidence. Visibility at the site ranges from 10 to 30 metres, allowing for clear observation of the reef structure. The site experiences mild currents, though divers must remain aware of boat traffic on the surface. Water temperatures fluctuate significantly between 2°C and 20°C, necessitating appropriate thermal protection such as a wetsuit or drysuit depending on the season. Access to this site is exclusively by boat, requiring coordination with local operators or dive buddies.

The Caroline Rose is a wooden schooner resting on the floor of Lake Huron in Big Tub Harbour. This wreck site sits at depths ranging from 10 to 17 metres, with an average depth of 12 metres. Divers experience mild currents and visibility typically between 5 and 10 metres. The vessel offers a well-defined structure for intermediate divers to explore, though the wooden construction presents specific entanglement hazards. Due to water temperatures fluctuating between 2 and 20 degrees Celsius, appropriate thermal protection such as a drysuit or thick wetsuit is essential for all dives. Access to this site requires a boat.

Dave's Bay is a shallow freshwater site located in Big Tub Harbour, Canada. The topography consists of a flat reef that maintains a consistent depth of 6 metres throughout the area. With no significant current, the site is well-suited for beginner divers looking to practice skills. Visibility typically ranges between 5 and 10 metres. Divers can access the water via shore or boat. Water temperatures fluctuate significantly throughout the year, ranging from 2 to 20 degrees Celsius. Due to these cold conditions, particularly outside of the summer months, appropriate thermal protection such as a drysuit is recommended.

The Arabia is a freshwater wreck located in Big Tub Harbour, resting at depths between 30 and 37 metres. This advanced dive requires boat access and is characterised by strong currents and variable visibility ranging from 5 to 18 metres. Due to the depth and cold water temperatures, which fluctuate between 1 and 19 degrees Celsius, a drysuit is recommended. The wreck structure presents specific hazards including entanglement risks and low visibility. Divers should possess solid buoyancy control and careful gas planning skills to manage the demanding conditions at this site.

Dunks Bay in Big Tub Harbour provides a sandy beach entry, offering a more accessible alternative to the rocky coves found elsewhere in Fathom Five National Marine Park. This site is suitable for beginner snorkellers due to its shallow nearshore waters. Conditions are generally mild, though the freshwater environment of Georgian Bay remains cold throughout the year, with temperatures ranging from 2C to 20C. A wetsuit is recommended for comfort. Divers and snorkellers should be aware of potential surf and the risks associated with cold water. Parking is available for visitors. Species recorded around this area include round goby, snails, lake trout, American crayfish, pike, common carp, and small mouth bass.

The Tugs in Big Tub Harbour consist of four small steam tugs resting in shallow freshwater. This site is accessible via a shore-side wooden deck, making it suitable for beginners. The Alice G is the most intact vessel, featuring a visible engine and boiler. Depths range from 3 to 12 metres, with an average of 6 metres. Visibility typically spans 12 to 24 metres. Conditions include mild currents and water temperatures that vary from 1 to 19C. Divers and snorkellers should remain aware of boat traffic in the harbour. Facilities at the site include parking, toilets, and changing rooms.