Common Eagle Ray (Myliobatis aquila), swimming above a rocky reef, Madeira, Portugal, Europe, Atlantic Ocean
Norbert Probst/imageBROKER/© Norbert Probst/imageBROKER
Off Dravuni Island lies part of the Great Astrolabe Reef, which, at about 65 kilometers (40 miles) long, is the fourth-largest barrier reef in the world. There’s not a lot of new reef growth, and crown of thorns—a kind of starfish that kills coral—are starting to show up, but because the reef is far from large towns, it’s still pretty healthy. Snorkelers can find a good variety of life, from tiny rockfish that look like fluttering confetti to eagle rays and sea horses, as well as sharks you’d probably rather not be surprised by.