formed of stony acropora and porites corals. The reefs form platforms and sometimes lagoons along the coast and occasional other features such as cylinders (such as the Blue Hole (Red Sea) at Dahab). These coastal reefs are also visited by pelagic species of Red Sea fish, including some of the 44 species of shark. It contains 175 species of nudibranch, many of which are only found in the Red Sea. The Red Sea also contains many offshore reefs including several true atolls. Many of the unusual offshore reef formations defy classic (i.e., Darwinian) coral reef classification schemes, and are generally attributed to the high levels of tectonic activity that characterize the area. The special biodiversity of the area is recognized by the Egyptian government, who set up the Ras Mohammed National Park in 1983. The rules and regulations governing this area protect local marine life, which has become a major draw for diving enthusiasts. Divers and snorkellers should be aware that although most Red Sea species are innocuous, a few are hazardous to humans. Other marine habitats include sea grass beds, salt pans, mangrove and salt marsh. Desalination plants There is extensive demand for desalinated water to meet the needs of the population and the industries along the Red Sea. There are at least 18 desalination plants along the Red Sea coast of Saudi Arabia which discharge warm brine and treatment chemicals (chlorine and anti-scalants) that bleach and kill corals and cause diseases in the fish. This is only localized, but it may intensify with time and profoundly impact the fishing industry. Trade The Red Sea serves an important role in the global economy, with cargo vessels travelling between the Indian Ocean and the Mediterranean Sea every year, thus shortening the path between Asia and Europe almost twice (as compared to travelling around Africa via the Atlantic Ocean). Tourism The sea is known for its recreational diving sites, such as Ras Mohammed, SS Thistlegorm (shipwreck), Elphinstone Reef, The Brothers, Daedalus Reef, St.John's Reef, Rocky Island in Egypt and less known sites in Sudan such as Sanganeb, Abington, Angarosh and Shaab Rumi. The Red Sea became a popular destination for diving after the expeditions of Hans Hass in the 1950s, and later by Jacques-Yves Cousteau. Popular tourist resorts include El Gouna, Hurghada, Safaga, Marsa Alam, on the west shore of the Red Sea, and Sharm-el-Sheikh, Dahab, and Taba on the Egyptian