Blue Hole

Dahab, South Sinai, Egypt

A near-circular submarine sinkhole on the coast several km north of Dahab, Egypt, in the Gulf of Aqaba. Opens to the sea at approximately 6 m through a notch in the reef (The Saddle); a 26-m-long tunnel (The Arch) through the outer reef wall has its ceiling at 55 m and its bottom at ~120 m on the seaward side. The recreational dive follows the inner wall; the Arch is a technical dive. The site has a long documented history of fatalities — over 100 deaths since 1997 — largely from divers attempting The Arch beyond their training.