Amazon River

Amazon estuary is about 325 km wide.

An excerpt from the article 20 facts about Amazon River

Within it, there is a giant river island, Marajó, which is flanked on both sides by the Amazon River. It occupies an area of 40,100 km2.

Located almost on the equator, Marajó has 20 major rivers and is covered with savanna vegetation and palm swamps.