The Cluster of Excellence The Ocean Floor – Earth’s Uncharted Interface aims to initiate a new chapter in ocean-floor research by quantifying exchange processes at this significant boundary layer and their roles in the Earth system. This will be achieved by: (1) deciphering processes that control the transport of biogenic particles to the ocean floor and their transformation under changing climate conditions (2) balancing the transfer of carbon and other elements between the ocean floor and seawater; (3) understanding how ocean-floor ecosystems react to environmental changes, and (4) developing scenarios for a ›warmer-than-present world‹ from ocean-floor climate archives with the help of climate models. These scientific tasks demand the use of novel technologies for ocean-floor observation and sampling, highly sensitive analytical methods, and an expanded application of numerical models. Because of their scientific and technological complexity, the stated goals can only be achieved through interdisciplinary research.