The northeast coastline of Marajó faces the Atlantic Ocean. The outflow from the Amazon between January and July is so great that the sea at the mouth is made up of freshwater for some distance from shore. The city of Belém lies to the south across the southern fork (also called the Pará River) of the river's mouth. The island sits almost directly on the equator.

The island was the site of an advanced pre-Columbian society, the Marajoara culture, which existed from approximately 400 BC to 1600 AD. The island has been a center of archaeological exploration and scholarship since the 19th century. Scholars from the 1980s forward have divided the pre-Columbian period into the Ananatuba phase (c. 1100–c. 200 BC), the Mangueiras phase (c. 1000 BC–c. 100 AD), the Formiga phase (c. 100-400 AD), the Marajoará phase (c. 400-1200 AD), and the Aruã phase (1200-1500 AD).

When someday comes you'll need to get in.

When someday comes you'll need to be able to get around.