Horse Prairie is a freshwater snorkel site located on the western shore of Clark Canyon Reservoir. It features one of the few sandy entry points on the reservoir, making it accessible for shore entry. The site is suitable for beginners, though conditions vary due to the fine sediment, which is easily disturbed and can reduce visibility to less than 3 feet. Water temperatures are cool, ranging from 2-13°C in spring and 15-21°C in summer. Wetsuits are recommended to prevent hypothermia during prolonged exposure. Facilities at the site include parking and toilets.

Armstead Island in the United States is a freshwater site featuring a submerged rocky perimeter that functions as a reef and artificial reef. Accessible by boat or paddleboard, the site offers a secluded environment for snorkelers. Conditions are variable, with visibility heavily influenced by wind. The water temperature is approximately 36°F (2°C), necessitating appropriate thermal protection for all water activities. Divers and snorkelers should be aware of potential boat traffic in the area. Facilities available at the location include parking, toilets, showers, changing rooms, a rinse station, air fills, equipment rental, a cafe, first aid, a dive shop, boat charters, guided tours, and gear storage.

Lewis & Clark Recreation Area, located near the historical Camp Fortunate site, offers shallow margins for snorkelling near the boat docks. The site features both reef and artificial reef structures. Conditions vary, with water temperatures reaching as low as 34-36°F (1-2°C) in early April. Due to the presence of heavy motorized vessel activity, snorkellers must remain vigilant. The site is accessible from the shore and is suitable for beginners, though the overall rating for snorkelling is 1/5. Facilities include parking, toilets, showers, changing rooms, a rinse station, air fills, equipment rental, a cafe, first aid, a dive shop, boat charters, and guided tours.

Beaverhead Campground serves as a shore entry point for snorkelling on the northeast end of Clark Canyon Reservoir. Located near the dam, the site features a rocky shoreline that provides better visibility than the siltier southern areas of the reservoir, although overall water clarity remains low. Conditions are characterised by consistently cold water temperatures, typically ranging from 1 to 5°C during spring and autumn. This site is suitable for beginners who are prepared for the cold, though time in the water should be strictly limited to prevent hypothermia. Facilities available at the site include parking and toilets.