Tytoona Cave is a stream cave in Sinking Valley in central Pennsylvania, near Arch Spring, Tyrone, and Altoona. Known in the historic record since at least the late 18th century, it was earlier called Sinking Valley Cave and Arch Spring Cave, and it also figures in local folklore from the 1750s. The cave begins in a deep sinkhole where streams join before entering a broad passage. Failed tourist development, later flooding, and some damaged formations have affected the interior. The walkable cave extends about 900 feet to a sump, while the full system runs about 4,200 feet toward Arch Spring. After a fatal 1988 dive, underwater access was tightly restricted, and the site is now overseen by a volunteer conservancy.