The Amazon River basin and the waters in the Atlantic Ocean into which the Amazon flows are home to the world's most diverse ecosystems. This region embodies a rich history of scientific discovery.

Yes, the Amazon River meets the Atlantic Ocean along the northeastern coast of Brazil in a massive, high-fidelity display of hydrologic power. Unlike many rivers that form a traditional delta, the Amazon discharges so much water—roughly 209,000 cubic meters per second—that it creates a "freshwater plume" that extends hundreds of miles into the ocean. This plume is so powerful that it actually dilutes the salinity of the Atlantic and changes its color for a vast area visible from space. At the mouth of the river, which is about 325 kilometers (202 miles) wide, the interaction between the outgoing river current and the incoming ocean tide creates a famous natural phenomenon known as the Pororoca, or tidal bore. This results in powerful waves that can travel several miles upriver. The meeting point is a critical ecological zone where freshwater and marine nutrients mix, supporting a unique array of biodiversity, including the famous Marajó Island, which is the largest fluvial island in the world, sitting right in the mouth of the river.