Ice Caves

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crystal ice cave
Crystal Ice Cave in Lava Beds National Monument, California.

NPS photo.

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Introduction

The term “ice cave” requires some clarification because it has been applied to caves that form in ice and caves that form in rock.

  • Ice caves that form in ice are called Glacier Ice Caves. Meltwater moving through glaciers forms this type of ice cave. Learn more about Glacier Ice Caves.
  • Caves formed in rock that contain ice all year-round are referred to as Ice Caves. These caves may contain very large ice formations on the floors, walls, and ceilings of the cave.

An Underground Icebox

Caves are very well insulated with constant temperatures reflecting the average temperature of the region where they form. Summer high temperatures and winter lows have almost no effect underground. In some instances, the shape of cave passages may make a trap for cold air that sinks into the tube in the winter and remains cold through the summer.

The wet surfaces caves and transparent nature of ice make for a delightful light show in the ice caves. Ice caves are well represented in our National Parks with such caves found at Craters of the Moon National Monument (Idaho) and at Sunset Crater National Monument (Arizona).

Changing Climate

Unfortunately, with our climate slowly warming, the ice caves are warming too. And warmer caves in some cases has meant too warm for ice. This has been very well documented at Lava Beds National Monument (California) by park staff and volunteer researchers with the Cave Research Foundation. The ice is slowly disappearing from many caves. Lovely translucent icicles are vanishing, and floors of cave ice are melting away to reveal the dark rock below. The loss of ice is permanently removing some beautiful features from these National Park caves. It could have a big impact on park wildlife as water supplies melt and dry up.

Find Your Park—Ice Caves

The following is a partial list of National Park Service units that include ice caves:

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Last updated: February 8, 2021

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