It’s 186 miles long, 12 miles wide, and populated with 500 species of tropical fish. The Ningaloo Reef, 700 miles north of Perth on Australia’s west coast, sees significantly fewer visitors per year than the Great Barrier Reef. Plus you can pull on your fins at the beach and swim out to it in minutes. If you’ve got the time, the 11-day road trip from the hub of Perth is worth it. Along the coastal highway from the city, stop at Monkey Mia, a resort where a pod of wild bottlenose dolphins feeds off the beach (doubles, $238). Take a catamaran trip to Shark Bay to check out a huge colony of dugongs—like manatees with fluked tails (yacht charters, $80 per person). Then make for Exmouth or Coral Bay—good bases to paddle out to Ningaloo to swim with giant, gentle whale sharks and spot migrating humpback whales.