Blue Hole, Castalia, Ohio
Six miles west of Sandusky, Ohio, on Route 101. The depth of the Blue Hole is unknown. The visible depth is apparently 50 or 60 feet. It finds its source in an underground river and maintains a temperature of 46 degrees, winter and summer. It is not affected by floods or drought. The volume of water flowing from this marvelous spring is seven million gallons daily, sufficient to supply a city of 75,000 population.