Post Office Cave

Post Office Cave received its name from a specific interior rock formation that early explorers thought resembled a series of mailboxes. The basalt formations sit side-by-side along the cave wall, closely mimicking a postal station. It is one of the most uniquely named lava tubes within the California monument.

Post Office Cave is known as a highly complex lava tube system with multiple levels, tight squeezes, and confusing junctions. Explorers must be highly proficient in navigating cave passages and often have to crawl on their hands and knees over rough rock. It is recommended only for experienced cavers due to its labyrinthine layout.

The cave is located within Lava Beds National Monument in Northern California. The park protects hundreds of lava tubes formed by ancient eruptions of the Medicine Lake Volcano. Post Office Cave is situated along the main park road and requires scrambling down a rocky entrance to access.

Because of its intense complexity, you absolutely need a reliable helmet, multiple strong light sources, and thick knee pads. The cave contains low ceilings, jagged breakdown piles, and tight passages that pose a physical hazard to the unprepared. The National Park Service strongly recommends carrying a detailed cave map and never entering this specific cave alone.