Hauser Causeway is a shallow artificial reef site located where Lake Helena meets the Hauser Reservoir. Divers and snorkellers can expect depths ranging from 1 to 4 metres, with an average depth of 2 metres. Conditions are characterised by mild currents and low visibility, typically between 1 and 3 metres. The water is very cold year-round, with temperatures recorded as low as 0.5°C in early April, making drysuits or thick wetsuits essential. Access is available via both shore and boat. Due to the potential for boat traffic, cold water, and limited visibility, divers should exercise caution. Facilities at the site include parking, toilets, and a cafe.

Devil's Elbow, located within the Gates of the Mountains, offers freshwater diving and snorkelling access from a small beach at the campground. The site features drop-offs near the boat docks, with depths ranging from 5 to 21 metres and an average depth of 8 metres. Conditions include mild currents, though water temperatures can be very cold, particularly in spring and at depth, presenting a risk of hypothermia. Divers should remain aware of boat traffic in the area. Facilities at the site include parking, toilets, and a cafe. Typical dives last approximately 45 minutes. This site is best suited for intermediate divers, while snorkelling is rated 2 out of 5.

Clark's Bay is a freshwater reef site located within the Gates of the Mountains, offering a roped-off sandy beach for easy shore entry. The site features shallow water, making it suitable for beginner snorkellers. Conditions at the site are variable, with mild currents and potential for low visibility. Divers and snorkellers should be aware of the cold water temperatures and the presence of a thermocline, which pose a risk of hypothermia outside of peak summer months. Boat traffic is a known hazard in this area. Facilities available at the site include parking and toilets.

York Bridge Fishing Access Site, located within the Gates of the Mountains, offers a river-like diving experience where the Missouri River flows into the reservoir. The site features a rocky bottom and is accessible via a shore entry. Divers should be prepared for moderate currents and potentially very cold water temperatures, which can drop to 33°F in early April. The site is best suited for intermediate divers due to these environmental factors. Facilities at the location include toilets. Visitors should be aware that toxic blue-green algae blooms can occur, which may impact water safety.

Coulter Campground in the Gates of the Mountains offers a freshwater drop-off experience accessible only by boat. The site features a prominent overhanging rock wall that descends into a pool reaching depths of approximately 9 metres. Divers and snorkellers should be prepared for variable conditions, including cold water and potential thermoclines. Due to the nature of the terrain and the requirement for boat access, this site is best suited for intermediate divers. Toilets are available at the campground for visitor use. As this is a freshwater environment, divers should be aware of the potential for low visibility and entanglement hazards.

Meriwether Picnic Area in the Gates of the Mountains features a limestone wall topography that drops to depths of 1 to 10 metres, with an average depth of 5 metres. This freshwater site is accessible by both shore and boat, offering a 3 out of 5 rating for snorkelers. Conditions vary, with mild currents and significant seasonal temperature fluctuations. Water temperatures in early April are very cold, ranging from 1 to 2 degrees Celsius, requiring a wetsuit. Summer temperatures rise to between 21 and 26 degrees Celsius. Snorkelers should remain aware of boat traffic in the area. Toilets are available at the site.

The Old Canyon Ferry Dam and Power Plant features the submerged remnants of an 1896 timber-crib dam and power station. Divers and snorkellers can explore the foundations and the massive stone and timber structures of the old spillway. Located 2414 metres from shore, this site requires boat access. Conditions are variable with visibility ranging from 3 to 8 metres and depths reaching 24 metres. The site presents hazards including entanglement risks, overhead environments, deep water, and significant boat traffic. Water temperatures fluctuate seasonally, with cold water posing a risk of hypothermia outside of the summer months. This site is suitable for advanced divers.

Court Sheriff Bay, located on the western shore of the Gates of the Mountains, offers a gentle entry from the shore. This freshwater site features rocky outcroppings and a gradual slope, reaching depths between 1 and 8 metres with an average of 4 metres. Visibility typically ranges from 3 to 8 metres. The site is suitable for beginners, though snorkellers should remain aware of boat traffic and the risk of cold water. Water temperatures vary significantly by season, ranging from 1°C to 5°C in April to 18°C to 24°C during the summer months. Facilities at the site include parking, toilets, and showers.