Read the following passage:

The ___(X)___ Barrier Reef is the world's largest coral reef system, located in the Coral Sea off the coast of Australia. It is home to a diverse array of marine life, including over 1,500 species of fish, 400 species of coral, and 4,000 species of mollusks. The reef is also home to many endangered ___(Y)___, including the dugong and the green turtle. The Great Barrier Reef is a popular tourist ___(Z)___, attracting millions of visitors each year who come to snorkel, dive, and explore the diverse marine life.