The Ocean Regulation of Climate by Heat and Carbon Sequestration and Transports (ORCHESTRA) data set comprises hydrographic data, including measurements of temperature, salinity and currents, complemented by bathymetric, meteorological and stable isotope data. The study area was the South Atlantic Ocean and Southern Ocean, including the Weddell and Scotia Seas and Drake Passage. The data were collected by research cruises, beginning March 2016. Shipboard data collection involved the deployment of conductivity-temperature-depth (CTD) packages and Lowered Acoustic Doppler Profilers (LADCP) in the study area. Continuous measurements of current velocities (using vessel mounted ADCPs, VMADCPs), bathymetry and surface ocean and meteorological properties were collected throughout each cruise. The ORCHESTRA programme aims to advance the understanding of, and capability to predict, the Southern Ocean's impact on climate change via its uptake and storage of heat and carbon. It represents the first fully unified activity by the Natural Environment Research Council (NERC) institutes as part of the Long-Term Multi-centre Science (LTMS) along with other UK research institutes, more specifically the British Antarctic Survey (BAS), National Oceanography Centre (NOC), British Geological Survey (BGS), Plymouth Marine Laboratory (PML), Sea Mammal Research Unit (SMRU), Centre for Polar Observation and Modelling (CPOM) and the Met Office Hadley Centre. The programme was divided into three Work Packages with the following Principal Investigators for each: WP1 (Interaction of the Southern Ocean with the atmosphere), led by Liz Kent from NOC; WP2 (Exchange between the upper ocean mixed layer and the interior), led by Dave Munday from BAS and WP3 (Exchange between the Southern Ocean and the global ocean), led by Yvonne Firing from NOC. The overall programme is led by Andrew Meijers from BAS. The majority of the data will be managed by the British Oceanographic Data Centre (BODC), with a minority of data sets being submitted to the BAS Polar Data Centre (BAS-PDC) and atmospheric data from MASIN aircrafts submitted to the Centre for Environmental Data Analysis (CEDA).