This project focuses on the Amazon River-to-tropical Atlantic Ocean continuum because of both its immense scale and its apparent sensitivity to climate variability and anthropogenic forcing. The river’s effect on the ocean depends not only on the river hydrology, but what the river carries and how those components are modified during transit from their terrestrial or aquatic origins. We brought together limnologists and oceanographers in an integrated project to improve our understanding of carbon exchange between the atmosphere and this tropical river continuum, focusing on the lower reach, nearshore, and offshore tropical Atlantic, with the goal of improving predictive capabilities under differing climate change scenarios.