1. Great Barrier Reef, Australia 2. Galapagos Islands, Ecuador 3. Silfra Fissure, Iceland 4. Red Sea, Egypt 5. Grand Cayman, Cayman Islands 6. The Maldives 7. Palau, Micronesia 8. Cozumel, Mexico 9. Belize Barrier Reef 10. Sipadan Island, Malaysia