A large deep pool, when Giantess Geyser is in an inactive phase it is still boiling at the center of the pool. Thin, solidified sinter lines the edge of the clear pool and the runoff channel is full of bright orange thermophiles. Giantess Geyser eruptions are highly infrequent—none to 41 per year—but impressive in size, reaching 200 feet (61 m). From these eruptions, Giantess Geyser has been observed to be directly connected to many of the surrounding features.

Giantess Geyser has an average temperate of 196°F (91.1°C), an average pH of 8.1, and an average conductivity of 1984 uS/cm.

Geysers

Geysers have constrictions in their plumbing systems that prevent water from moving freely to the surface where heat would escape. Water beneath the constrictions creates a buildup of steam. Eventually the steam pushes water past the constrictions and the geyser erupts.

Upper Geyser Basin

The majority of world’s active geysers are in the Upper Geyser Basin, including Old Faithful. Only four other places in the world have large concentrations of hydrothermal features: Russia (Kamchatka), Chile, New Zealand, and Iceland.

The heat for the hydrothermal features comes from Yellowstone’s volcano. Molten rock or magma may be as close as 3-8 miles (5-13 km) underground. Rain and snow supply water that seeps down several thousand feet (more than a kilometer) below the surface where it is heated.

Underground cracks form a natural plumbing system. Hot water rises through the plumbing to produce hot springs and geysers.

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.