As the name suggests, Wall Pool is a pool with a wall and an overhanging shelf of sinter to the west. Wall Pool is related to Black Opal Pool and Black Diamond Pool as a hydrothermal explosion crater. Wall Pool was created by one of the steam explosions in the early 1900s. Wall Pool exploded again in 2005, but activity has continued to decrease. It actively boils and the edges of the pool and surrounding runoff contain orange and yellow thermophiles.

Wall Pool has an average temperate of 190.5°F (88°C), an average pH of 7.9, and an average conductivity of 1833 uS/cm.

Hot Springs

Hot springs are the most common hydrothermal features in Yellowstone. Their plumbing has no constrictions.

Superheated water cools as it reaches the surface, sinks, and is replaced by hotter water from below.

This circulation prevents water from reaching the temperature needed to set off an eruption.

Use Caution in Hydrothermal Areas

• Stay on boardwalks and designated trails.
• Hydrothermal water can severely burn you.
• Never run, push, or shove.
• Supervise children at all times.
• Do not scratch hydrothermal mats.

You are responsible for your safety.

Think safety, act safely. Yellowstone is a dangerous place.