By all accounts, the future of the Great Barrier Reef seems bleak. Mass tourism, overfishing, water pollution and coral bleaching caused by global warming are all playing a part in damaging this fragile natural wonder. During your visit, be sure to tread lightly. Choose trips and activities that are operated in an ecologically sensitive manner. Never touch the coral when diving or snorkeling—keep your fins well clear of it. And remember to take all your trash with you.