The correct answer is option 3: Australia. The Great Barrier Reef is a famous natural wonder located in the Coral Sea off the coast of Queensland, Australia. It is the largest coral reef ecosystem in the world, stretching over 2,300 kilometers (1,400 miles). The reef is home to a diverse range of marine life, including thousands of species of fish, turtles, dolphins, and sharks. It is a popular tourist destination for snorkeling, scuba diving, and boat tours. With its vibrant coral formations and turquoise waters, the Great Barrier Reef is an iconic symbol of Australia`s natural beauty.