The Great Barrier Reef is one of the several wonders of the world,. bBeing the world’s largest coastal ecosystem, its ginormous size can be seen from outer space. The Great Barrier Reef is the world's largest coral reef system composed of over 2,900 individual reefs and 900 islands stretching for over 2,300 kilometres. Being so special, this reef depends highly on our input to keep it healthy so the world has time to enjoy its majestic wonders.