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A few kilometres north of Dahab, the Blue Hole is a near-perfect circular sinkhole plunging some 90 metres straight down through the reef. From the surface it is a serene disc of deep sapphire ringed by shallow coral, and for snorkellers and recreational divers hovering along its rim it is simply beautiful, a wall of fish and coral dropping into the blue.

Its darker fame comes from the deep: a submerged arch at 55 metres has lured technical divers to their deaths, earning it a grim nickname and a cliffside of memorial plaques. Most visitors never go near that danger, coming instead to snorkel the shallows, sip tea at the row of Bedouin cafés, and take in one of the Red Sea's most striking natural formations.