At the mouth of the Amazon, Marajó is the world’s largest fluvial (that is, river) island. With an area of 40,100 square kilometers (15,500 square miles), it is just a little smaller than Switzerland yet with a population of only some 250,000 residents. During the rainy season, much of this flat island becomes a vast lake. It is a popular destination for surfers, given the large waves created by the island’s tidal bore, and bird-watchers, who come in search of colorful species from scarlet ibises to blue herons.
