This study documents a unique and highly efficient process of particulate organic carbon (POC) transfer from a major river estuary to the deep ocean. By providing the first direct observations of Congo River-derived POC at significant depths, the study reveals how both turbidity currents and tidal forces facilitate the movement of large carbon quantities to the Congo deep-sea fan, 1,200 km from the river mouth. Given that the Congo River contributes about 7% of the total organic carbon from the world's rivers, the findings highlight a potentially underestimated component of the global carbon cycle, making this research crucial for refining carbon cycle models and understanding carbon dynamics along the land-ocean continuum.