The Blue Hole is a vertical underwater cave more than 120 m deep, surrounded by the most beautiful reef of the Red Sea. It is located 15 km from the Egyptian resort of Dahab. Tourist guides call it one of the best dive sites in the world, but it is also known as the “graveyard of divers.” The bodies of the daredevils who have never conquered Blue Hole do rest at the bottom of this karst sinkhole. There are no official statistics, but about 150 people have died there over the past two decades. In their honor, a spontaneous memorial with nameplates was created on one of the coastal cliffs. Most accidents occur when inexperienced divers perform a dive without special technical diving equipment into the Arch, a long horizontal tunnel connecting the cave to the sea. They die from nitrogen narcosis, disorientation, and depletion of air supply during ascent. Therefore, only divers qualified as Advanced Open Water Divers are allowed to explore Blue Hole. The colorful reef is full of a variety of sea creatures, from colorful parrotfish to predatory barracudas and moray eels. One of the cave walls is covered by a large colony of the rare coral Pachyseris Speciosa called “elephant skin.”