Sudan is famous for encounters with pelagic. A narrow plateau starting at 20 Metres stretches out for 50-75 m then drops off at 40 m. It drops to 600 m on all sides. Lots of grey reef sharks, hammerheads in big schools, silvertips and sometimes silky sharks. It's easy to have manta encounters and the coral as well as the fish life is extraordinary with schools of barracuda and trevally. Visibility is excellent: 20-30m).
Sudan has also amazing wrecks, like the Wreck of the Umbria: It's a spooky castle covered by corals loaded with 36000 aircraft bombs, cars, wine bottles and so on. The site is visited by mata rays, whale sharks and, at night, tiger sharks. You'll probably be alone on the wreck due to the small numbers of divers visiting the country.