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 (Red Sea)
However, the Sinai Peninsula was occupied by Israel during the Six-Day War of 1967 (with Israel occupying the territory until 1982). The first people to dive the hole with modern scuba diving equipment were Israeli divers led by Alex Shell, who noticed the underwater arch in 1968. By the time Israel handed the Sinai Peninsula back to Egypt in 1982, the Blue Hole had developed a reputation as a diving site amongst the international scuba diving community.