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.

White Sandy Recreation Area is situated at the confluence of Prickly Pear Creek within the Gates of the Mountains. This freshwater site features a sandy shore entry and provides views of the Big Belt Mountains. Divers and snorkellers should be aware of variable conditions, including low visibility and distinct thermoclines. Deeper water remains cold, often ranging between 4 and 9 degrees Celsius, due to stratification and river inflow. The mixing of creek and lake water creates temperature gradients throughout the site. It is suitable for beginners and offers accessible facilities including parking and toilets.

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.

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.

The Junkyard is a freshwater artificial reef located at the northern end of the reservoir in the Gates of the Mountains. This site features submerged mid-20th-century car parts and the foundations of old houses. Divers can expect depths ranging from 8 to 15 metres, with an average of 9 metres. Conditions include mild currents and visibility between 5 and 7 metres. Due to water temperatures that can drop below 5°C, a drysuit or thick wetsuit is essential to mitigate the high risk of hypothermia. The site is accessible by boat or from the shore and is suitable for intermediate divers. Night diving is permitted, with typical dives lasting 40 minutes.

Kim's Marina in the Gates of the Mountains offers a shallow freshwater dive experience suitable for beginners. Depths range from 1 to 8 metres with an average of 4 metres. Divers encounter mild currents and visibility typically between 5 and 10 metres. The site features both shore and boat entry options. Due to significant seasonal temperature variations, appropriate thermal protection is required, with drysuits or wetsuits recommended at the beginning and end of the season. Facilities include parking, toilets, showers, changing rooms, a rinse station, and air fills. Dives typically last 30 minutes. Divers should monitor their surroundings closely due to variable visibility and manage cold water temperatures.