Carved into a reef, 8km north of Dahab, is Egypt’s most infamous dive site. The Blue Hole is a gaping sinkhole that drops straight down – some say as deep as 130m. Exploring the deeper depths should be left to experienced technical divers, but there's plenty to discover close to the surface. The outer lip is full of marine life and a reasonable plunge into the hole is somewhat akin to skydiving. Depth: 7m to 27m. Rating: intermediate to advanced. Access: shore.

　　Advanced divers can enter at the Bells, a narrow breach in the reef table that forms a pool close to shore. From here, divers descend through a chimney, exiting at 27m on a ledge that opens to the sea. Swim south along the wall, a saddle in the reef at 7m allows entry to the Blue Hole. As long as divers monitor their depth carefully, they can finish up by swimming across the sinkhole towards shore.

　　Unfortunately, the site has claimed several lives, mainly thrill-seekers venturing well below the sport-diving limit. The trap is an archway at approximately 65m, which connects the sinkhole to the open ocean. Under-prepared solo divers attempting to find this archway have succumbed to narcosis, missed the archway entirely, lost all sense of direction or simply run out of air. In 2017 these dangers were highlighted yet again when renowned Irish freediving safety diver Stephen Keenan tragically died when rescuing another freediver who had become disorientated.