The 50,000-sq-km Ilha de Marajó, slightly larger than Switzerland, lies at the mouth of the Amazon River and is generally considered to be the largest river island in the world; writer Peter Matthiessen once described it as the Amazon's cork. (Some argue Marajó doesn't qualify because part of the island faces the open ocean.) It was the ancient home of the Marajoaras indigenous culture, notable for their large ceramic burial urns. Marajó remains a world apart, where bicycles outnumber cars and water buffalo graze around town.
Only the island’s eastern shore is accessible to tourists, with three small towns: Joanes (the smallest), Salvaterra (with the best beach but not much else) and Soure (the laid-back 'capital' of Marajó). The island’s interior is wetland, home to thousands of birds, including the graceful guará (scarlet ibis). Be aware that Marajó is very wet from January to June.