Blue Hole (Castalia)
The Blue Hole is a fresh water pond located in Castalia, Erie County, Ohio, in the United States. From the 1920s to 1990 the Blue Hole was a tourist site, attracting 165,000 visitors annually at the height of its popularity, partly because of its location on State Route 269, about southwest of the Cedar Point amusement park in Sandusky, Ohio.
Blue hole
The deepest blue hole in the world at 300.89 meters (987 feet) deep is in the South China Sea and is named the Dragon Hole, or Longdong. The second deepest blue hole in the world with underwater entrance at is Dean's Blue Hole, located in a bay west of Clarence Town on Long Island, Bahamas. Other blue holes are about half that depth at around . The diameter of the top entrance ranges typically from (Dean's Blue Hole) to (Great Blue Hole in Belize).