Ash Cave is part of the Hocking Hills State Park near Logan, Ohio. The cave is one of Ohio's most popular natural history attractions.

Ash Cave is located in a gorge of Black Hand Sandstone. The gorge extends approximately one-quarter mile. Thousands of years of erosion, principally caused by glaciation and a tributary of Queer Creek, which flows through the gorge, resulted in the cave. Sandstone is a very porous substance and much more susceptible to erosion than many other types of rocks. Ash Cave is the largest recess cave in Ohio. Water erosion created a recess in the sandstone that is approximately seven hundred feet long, one hundred feet deep, and ninety feet high. A small waterfall falls several hundred feet into the gorge at the front of Ash Cave.

Ash Cave is named for large amounts of ashes that early white settlers discovered in the cave. Purportedly deep piles of ashes existed, with at least one pile supposedly being three feet deep, one hundred feet long, and thirty feet wide. White settlers believed that Indians used Ash Cave for shelter and that the ashes resulted from the Indians' campfires. Archaeological evidence supports these conclusions. It appears that the Shawnee Indians especially used Ash Cave, perhaps as a place of rest, while traveling between villages in modern-day West Virginia and in central Ohio. Early white settlers used the cave as a church, until they could construct an actual building to house the congregation.

In 1924, the State of Ohio purchased 146 acres of land in the Hocking Hills. This purchase formally established Hocking Hills State Park. The State of Ohio eventually purchased additional land, including Ash Cave. First owned and operated by the Ohio Department of Forestry, in 1949, the Ohio Department of Natural Resources and the Ohio Division of Parks assumed control of Hocking Hills State Park.