Castle Geyser

Castle Geyser is a cone-shaped geyser in the Upper Geyser Basin of Yellowstone National Park with a large mineral structure built up over centuries. The surface displays stepped terraces and channels carved out from the main opening.

The mineral deposits forming this geyser began roughly a thousand years ago, confirmed through scientific analysis of the cone structure. An expedition of explorers named it in 1870, making it one of the park's earliest documented natural features.

The name comes from the geyser's resemblance to a castle tower, a connection visitors can see in its distinctive mineral structure. This tower-like shape made it instantly recognizable when explorers first encountered it.

Visitors should allow time to watch eruptions from a safe viewing area and maintain distance from the hot activity around the cone. Early morning or late afternoon often provides quieter viewing conditions with fewer crowds in the basin.

The mineral cone surface is so fragile that scientific measurements at its base remain impossible to obtain. This delicate nature helps preserve the structure but also makes it vulnerable to damage from careless footsteps.