United States of America
(2,561 ft/781 m). Crawling is required in the downstream portions of this cave where it connects to Labyrinth and Lava Brook Caves. Upstream (right) from the entrance are a few tight areas, one of which is 6 in (15 cm) wide at knee level. There is some stooping before the ceiling height allows walki
Listen to the audio guide for Thunderbolt Free on WIP — starts by itself when you arrive, even with the screen off