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 (New Mexico)
Since Santa Rosa, New Mexico is at an elevation of , it is necessary for divers to use high-altitude dive tables to compute the dive profile and decompression stops when diving in the Blue Hole.