One of the world’s greatest wonders, the Great Barrier Reef in Australia is a legendary coral ecosystem that covers 133,000 square miles, about the size of Japan, featuring more than 3,000 coral reefs. Not only does it bring the chance to dive or snorkel among an astounding array of marine life that includes more than 1,600 species of tropical fish, dolphins, rays, turtles, sharks and giant clams, but it offers a lesson on the effects of climate change. Sadly, it may be gone as soon as 2030 as increasing environmental challenges have been steadily eroding it for years. According to the Australian Conservation Foundation claims, a rise in ocean temperatures of just 3 to 5 degrees Fahrenheit, combined with more acidic water, could leave 97 percent of the Great Barrier Reef bleached and lifeless. If you visit, you’ll have a number of options, just keep in mind that it’s very fragile, so going with a knowledgeable guide not only helps to enrich the trip, but could also keep you from inadvertently harming the reef. There are tour operators that use large boats to take groups out with educators to explain the different types of coral, environments and challenges that face the reef as a whole, or you can get out on a smaller boat with a guide.