The oceanographic dataset collected during the Controls over Ocean Mesopelagic Interior Carbon Storage (COMICS) Project (2017-2022) dataset https://portal.medin.org.uk/portal/start.php?tpc=006_f8a4cf29aa9f5cd0b06ad894f4e06b49 The COMICS (Controls over Ocean Mesopelagic Interior Carbon Storage) project consists of observations, at sea, of particle flux and stable isotopes. It applies organic geochemical and molecular biological techniques to samples collected using nets and traps. The study areas are the tropical Atlantic and Southern Oceans. The results will be combined with models to quantify the flow of carbon in the ocean’s ‘twilight’ zone in order to accurately model global climate change. This ‘twilight’ zone is the part of the ocean between 100m and 1000m below the sea surface, where only a small amount of light from the sun can still penetrate. By investigating carbon dynamics in the ocean interior, COMICS will help to improve predictions of future global climate change. The COMICS project is led by the National Oceanography Centre and is a collaboration between the British Antarctic Survey and the universities of Queen Mary London, Liverpool, Oxford and Southampton. The project received funding from the Natural Environmental Research Council and runs between 2017 and 2022. 20180824 20210322