A fatal attraction: that is one dimension of the Blue Hole, a 100m-deep underwater pothole just off the shore of the Sinai Peninsula. This fissure has claimed many divers' lives, as becomes clear as you approach it; small shrines and memorials to lost loved ones line the route to the sea. But despite its notoriety, for the snorkeller who intends to descend only a few metres it is (weather-permitting) a relatively tame swim that gives you an amazing insight into what can exist just below the sur...