Montgomery Reef, Australia

It appears as a mirage around 12 miles off the Kimberley’s northwest coast, emerging from the warm Indian Ocean in a deluge of rushing whitewater and cascading mini-falls. Montgomery Reef, the largest inshore reef on Earth, spans more than 150 square miles and rises upward of 35 feet at low tide, creating what Sir David Attenborough described as “one of the greatest natural wonders of the world.” Western Australia experiences some of the highest tides in the world, averaging around 13 feet most days (nearly triple that at full moon). So while only a few sandstone islets appear over Montgomery Reef at high tide, the reef’s entire platform is revealed as the sea level drops, exposing a massive ecosystem of vast lagoons and a central mangrove island, along the myriad marine creatures they support—fish, reef sharks, six species of turtles, sea snakes, octopuses, dolphins, dugongs, and saltwater crocodiles. Situated between Camden Sound and Collier Bay, Montgomery Reef forms part of Lalang-garram/Camden Sound Marine Park, a crucial calving and nursery site for the largest humpback whale population on the planet.