Bahía Shark

Shark Bay, at the westernmost point of the Australian continent, was inscribed on the World Heritage List in 1991 and is one of the few properties on the planet recognised under all four of UNESCO's natural criteria. Its area is around 2.2 million hectares of water and land, with a coastline of more than 1,500 kilometres of shallow bays, peninsulas and islands.

Its most extraordinary feature is the stromatolites of Hamelin Pool: structures built by cyanobacteria that trap sediment and precipitate carbonate, forming rocky mounds that grow by millimetres per century. They are organisms of the same kind that dominated life on Earth for billions of years and that were responsible for oxygenating the atmosphere; seeing them alive and forming is a direct window onto the oldest ecosystems on the planet. They survive here because evaporation in an almost enclosed bay has doubled the salinity of the water, keeping out the organisms that would normally graze them away.

The bay also holds the largest and richest seagrass meadow known, with thousands of square kilometres covered by a dozen species. That meadow supports one of the largest dugong populations in the world, alongside bottlenose dolphins — those of Monkey Mia are famous for their interaction with people — turtles and sharks. On land, the bay's peninsulas and islands act as a refuge for threatened Australian mammals, with programmes to eradicate introduced predators and reintroduce species lost from the mainland.