Blue Hole (Red Sea)
The Blue Hole is a diving location on the southeast Sinai, a few kilometres north of Dahab, Egypt on the coast of the Red Sea.
Great Blue Hole
Initial measured depth of Great Blue Hole was which is the most often cited depth up to this day. An expedition by the Cambrian Foundation in 1997 measured the hole's depth as at its deepest point. This difference in measurement can be explained by ongoing sedimentation or by imprecision in measurements. The expedition's goal was to collect core samples from the Blue Hole's floor and document the cave system. To accomplish these tasks, all of the divers had to be certified in cave diving and mixed gases.