Pacific Tarn lake is the highest named lake in the United States, situated at an elevation of 13,420 feet. This freshwater site offers a unique high-altitude diving experience with depths ranging from 2 to 8 metres and an average depth of 5 metres. Divers access the water via the shore. Conditions are consistently cold, with summer temperatures between 10 and 15°C and near-freezing temperatures in winter. Visibility varies significantly from 1 to 15 metres. Due to the cold water, depth, and low visibility, this site is suited for intermediate divers. Typical dive times are approximately 18 minutes. Snorkelling is possible but rated 2 out of 5.

Jefferson Lake is a high-altitude glacial lake situated at 10,700 feet within the Denver Metro Reservoirs. The site features a distinctive underwater landscape defined by massive granite boulders that extend from the shoreline into the water. Divers and snorkellers can expect visibility ranging from 6 to 12 metres. This is a shore-entry site suitable for intermediate participants, with an average depth of 3 metres. Water temperatures are consistently cold, rarely exceeding 10°C and often dropping to 0-2°C due to the high altitude. Hazards include cold water and potential entanglement. Facilities at the site include parking and toilets.

Turquoise Lake at the Matchless entry offers a high-altitude freshwater dive experience near Leadville. The site features rocky drop-offs that descend from 6 to 30 metres. Divers should be prepared for consistently cold water year-round, with surface temperatures ranging from 2 to 18 degrees Celsius depending on the season. A dry suit is recommended for comfort. Visibility typically fluctuates between 6 and 9 metres. Access is via a shore entry at the boat ramp. Due to the depth, cold water, and potential for boat traffic, this site is best suited for intermediate divers. Snorkelling is also possible at this location.