Heppe Cave changes with the season. In summer there is a pond on the floor. In winter the same water is an ice floor. Few caves anywhere let you watch the same feature switch state twice a year, and it takes only a short hike to reach.
The ice comes from the way a lava tube handles air. Cold winter air is dense, sinks into the cave through its openings and settles, and cannot easily flow back out. That keeps the cave far colder than the desert above it, and water that seeps down through the rock freezes rather than draining. Come back in July and the floor has turned to standing water again.
Heppe sits among the least challenging caves at Lava Beds, with the walk in being most of the effort, which makes it a reasonable stop with children as long as everyone has a light and a helmet.
The monument occupies the northeastern flank of Medicine Lake Volcano in northeastern California, the largest volcano by area in the Cascade Range. It was established on 21 November 1925 and covers over 46,000 acres of lava tubes, cinder cones, spatter cones, pit craters, hornitos and maars. Twenty seven caves have marked entrances and developed access.
The monument is also where the Modoc War was fought in 1872 and 1873, by a band led by Kintpuash, known to settlers as Captain Jack, and the lava country itself was the defensive position they held.
A free caving permit from the visitor centre is required before entering any cave here.
Other places on the map within a couple of hours.
