Balcony Cave is named for a feature that tells you exactly how a lava tube works. Part way along, an optional scramble takes you up onto a balcony, a shelf running along the wall above the main floor. That shelf is not decoration. It marks where the surface of the molten lava river stood for long enough to leave a rim before the level dropped again.
A lava tube forms when the top of a moving lava flow chills and hardens while the inside keeps running. When the eruption stops, the molten interior drains away downhill and leaves a tunnel. If the level falls in stages rather than all at once, each pause leaves a line, a bench or a balcony on the wall. Reading those levels is how you work out what the flow was doing after the roof went on.
It is paired with Boulevard Cave next door and the two are usually visited together. Both are ranked moderately challenging: expect sections of low ceiling where you will be stooping, so kneepads and gloves are worth having, and a cave map helps.
Balcony appears regularly on the monument's closure list, so check before you drive out. Caves here close seasonally or year round for safety and for bat protection.
The monument lies on the northeastern flank of Medicine Lake Volcano, the largest volcano by area in the Cascade Range, in a landscape of cinder cones, spatter cones, pit craters and lava flows. A free caving permit from the visitor centre is required before you enter any cave, and you need a helmet and several light sources.
Check before you drive out. The monument currently lists Balcony among its closed caves. Lava Beds shuts tubes temporarily, seasonally, or for a whole year, either for safety or to protect the bats that roost in them, so read the closure list on the park site the morning you go.
Other places on the map within a couple of hours.
