Marajó Island is one of the world’s largest fluvial, or river, islands at the mouth of the Amazon.
Marajó lies in northern Brazil, between the main Amazon channel and the Atlantic Ocean. It covers about 40,000 square kilometres, although its exact area varies depending on how surrounding tidal and river channels are measured. The island is larger than several countries and is famous for extensive wetlands, grasslands and seasonally flooded forests.
The island’s position gives it a distinctive environment influenced by both freshwater and Atlantic tides. Water buffalo are widely associated with Marajó, and cattle ranching is an important local activity. The island also preserves evidence of the pre-Columbian Marajoara culture, known especially for its elaborate ceramics.
Marajó is often called a river island, but its waters are affected by tides because it lies near the Amazon’s estuary. Bananal Island, in central Brazil, is another enormous river island but is not at the mouth of the Amazon.