Dead Man's Hole, located south of Marble Falls in southern Burnet County, is a deep, well-like hole probably caused by gas pressure. It was discovered in 1821 by entomologist Ferdinand Lueders while he was in the area to study night-flying insects. The cave achieved notoriety during the Civil War as a dumping place for the bodies of Union sympathizers. The remains of several bodies were recovered from the cave in the late 1860s, but the presence of gas prevented extensive exploration. The gas evidently dissipated over time, for in 1951 a group of spelunkers from the University of Texas successfully descended the hole. They reported that Dead Man's Hole was seven feet in diameter at the surface and about 160 feet deep; at its base, the hole split into two "arms," one extending straight back for about fifteen feet, and the other sloping downward at a 45° angle for about thirty feet.
A Texas Historical Marker was erected for the landmark in 1998. Owner Ona Lou Roper deeded Dead Man’s Hole and its surrounding 6.5 acres as a park to Burnet County in 1999.