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.

Halfway Log Dump in Big Tub Harbour features a rugged shoreline defined by massive white boulders and the underwater extension of the Niagara Escarpment cliffs. This freshwater site offers a combination of reef and wall topography. Divers and snorkellers can expect visibility ranging from 5 to 20 metres. Conditions include mild currents and potential surf, with water temperatures varying significantly by season and depth, ranging from 2 to 20 degrees Celsius. Due to these cold water conditions, a dry suit or thick wetsuit is recommended. The site is accessible via a shore entry and provides parking and toilet facilities for visitors.

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.

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.

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 Forest City is a wreck dive located in Big Tub Harbour, Canada, within Fathom Five National Marine Park. Resting at depths between 18 and 46 metres, this site is suited for advanced divers with deep diving certification. The wreck is situated 1500 metres from shore and requires boat access. Divers encounter cold freshwater conditions ranging from 1 to 19 degrees Celsius, necessitating drysuit use. Visibility fluctuates between 5 and 25 metres. Hazards include boat traffic, entanglement risks within the structure, and the potential for nitrogen narcosis. Divers should maintain awareness of thermal status and decompression requirements throughout the typical 40-minute dive.

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.

Tobermory HBC is a shallow wreck dive located in Big Tub Harbour, Canada. Resting at an average depth of 6 metres, the site is accessible via a shore entry and features mild currents, making it suitable for beginner divers. Visibility is excellent, often reaching 30 metres. The site offers a 40-minute typical dive duration, though divers must remain aware of boat traffic on the surface and potential entanglement hazards within the wreck structure. Water temperatures fluctuate significantly throughout the year, ranging from 2°C to 20°C, with thermoclines common. Thermal protection is required for all dives.