#2 – Great Barrier Reef
Located in Australia, the Great Barrier Reef is one of the most popular attractions in the world. It is the largest coral reef on the planet, and has long been the most alluring place among scuba divers. However, more and more environmental changes appear to challenge this coral reef. One of the main problems is the rising ocean temperatures, which leads to the eroding of this reef. Some experts claim that this attraction will be completely gone a hundred years from now.