Blue Hole

Dahab's famous sinkhole is really two dive sites sharing an address. The one most people do is lovely and undemanding: drop through the Bells chimney, drift south along an outer wall stepped with coral, and glide over the shallow saddle into the sunlit bowl. The other - the Arch, a roughly 26-meter tunnel through the reef wall with its ceiling near 55 meters - belongs to technical diving, and the site's grim reputation was earned almost entirely by people who attempted it without the training, gas, or support it requires. No official count exists; conservative estimates put the deaths well past one hundred, and memorial plaques line the cliff above the entry. Dived within limits, it is a calm, current-free pleasure. The shaft itself bottoms out somewhere between about 92 and 120 meters depending on the survey.

The moment you come for: The Bells chimney entry; the saddle crossing into blue light; freediving culture at the surface; sobering memorial wall ashore.

Topography: A collapsed circular shaft in the fringing reef, its floor far below recreational depths, ringed by living coral walls

Entry: The classic dive enters at the Bells, a narrow chimney north of the hole, follows the outer wall south, and crosses the saddle at about 7 meters into the hole itself. Proof of certification is checked.

Hazards: The Arch has killed experienced divers as well as reckless ones - depth, narcosis, and a deceptive exit; freedivers and scuba traffic share the bowl; midday snorkeler crowds.

Permits & rules: Protectorate entry fee; guides and proof of certification required, with technical dives subject to additional checks.

Conservation: Inside the Ras Abu Galum protectorate; entry tickets fund management. The saddle's corals take heavy traffic - keep fins up.

Nitrox: Worth it here: profiles sit in the range where enriched air meaningfully extends no-stop time (with the training to use it).