Clarksville Cave, in Clarksville, Albany County, New York, is a horizontal cave system with about 4,800 feet of passage and three entrances. It is significant for having an unusually long recorded history for a New York cave. The earliest known petroglyph inside dates to 1811, and by 1818 Teunis Houghtaling had written a letter describing the cave. Together, these early records show that it was already known and notable in the early nineteenth century.