Mary Bay is a unique freshwater site in Grand Teton National Park defined by intense geothermal activity. Divers encounter active underwater geysers and fumaroles that vent water reaching 174°C into the cold lake environment, which averages 4°C at depth. This interaction creates extreme temperature gradients and dangerous thermoclines. The topography includes sandy bottoms marked by white mineral stains and fields of bubbles. Due to the depth of 21 to 27 metres, moderate currents, and low visibility ranging from 3 to 9 metres, this site is reserved for advanced divers. Shore entry is required, and divers must remain vigilant regarding boat traffic, entanglement risks, and down currents.

Yellowstone Lake Lodge offers a unique freshwater dive experience within a geologically active environment. Divers access the site via a shore entry, exploring depths ranging from 5 to 23 metres with an average of 10 metres. The topography features reef and artificial reef structures, alongside a wreck. Visibility typically fluctuates between 3 and 9 metres. The water is extremely cold, averaging 5°C, with hydrothermal vents creating localized hot spots and significant thermoclines. Divers should be prepared for mild currents, potential boat traffic, and rapid temperature variations. Due to the cold water and depth, a drysuit or thick wetsuit is recommended for all divers.

Gull Point in Grand Teton National Park offers a shallow freshwater snorkeling experience along a sandy beach. The site features a sandbar that emerges in late summer, providing a gentle shore entry into depths ranging from 1 to 5 metres. Visibility typically fluctuates between 3 and 9 metres. Due to the extremely cold water temperatures averaging 5°C, the risk of hypothermia is significant, and survival time is estimated at 20 to 30 minutes. Snorkellers should remain aware of boat traffic in the area. Given the severe cold, swimming is generally not recommended, and sessions are typically limited to 20 minutes.

The Spires is an artificial reef located in Grand Teton National Park, situated 2000 metres from shore. The site sits at depths between 8 and 15 metres, with an average depth of 12 metres. Divers must access the site by boat. Conditions include mild currents and visibility ranging from 3 to 10 metres. The environment is characterised by cold water and significant thermoclines, requiring appropriate thermal protection. Divers should be aware of hazards including boat traffic, entanglement risks on the structures, and the potential for decompression requirements. A surface marker buoy is essential for safe ascents due to overhead boat traffic.

Plover Point in the South Arm of Yellowstone Lake is a remote freshwater site accessible only by boat. The topography features sandy beaches and depths reaching 120 metres, with an average depth of 48 metres. Visibility varies significantly, ranging from 3 to 30 metres. Divers should be prepared for cold water conditions, as the average temperature is 5°C, limiting survival time to 20 to 30 minutes. Due to the extreme depth, potential for nitrogen narcosis, and decompression requirements, this site is suited for advanced divers. The area is also suitable for snorkelling, though the cold water remains a primary environmental factor for all water activities.

West Thumb in Grand Teton National Park offers a unique freshwater snorkeling experience where visitors can observe geothermal features such as the Fishing Cone and Lakeshore Geyser from the water. The site is characterised by the contrast between deep blue lake water and vibrant bacterial mats near the shore. Snorkelling here is suitable for intermediate participants, with depths ranging from 1 to 5 metres and an average of 2 metres. Entry is via the shore. Conditions include mild currents and visibility between 1 and 5 metres. Divers and snorkellers must exercise caution due to extreme temperature variations, cold water, and the presence of scalding geothermal vents.

Firehole is a shallow freshwater site in Grand Teton National Park, offering depths between 4 and 6 metres. Entry is via the shore, leading to an area characterised by strong currents that require careful monitoring. Visibility typically ranges from 5 to 10 metres. Due to geothermal activity, water temperatures can be extreme, and divers should check conditions closely before entry. The site is best managed by timing dives for slack water to mitigate the intensity of the current. Divers are advised to plan their route to swim against the current initially, ensuring an easier return leg.