The Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES) UK data set comprises hydrographic data, including measurements of temperature, salinity, currents and turbulence, supplemented by bathymetric and meteorological data. The study area is located within the Antarctic Circumpolar Current (ACC) in the southeast Pacific, Drake Passage and Scotia Sea regions of the Southern Ocean. Data collection began in December 2009 and ended in April 2014. The data were collected via a combination of research cruises in the southern hemisphere summer seasons. Three cruises were intended (UKD-1, UKD-2 and UKD-3) a further three cruises were completed (UKD-2.5, UKD-4 and UKD-5). Shipboard data collection involved the deployment of conductivity-temperature-depth (CTD) packages, accompanied by lowered acoustic Doppler current profilers (LADCPs), and Vertical Microstructure Profilers (VMPs) in a grid pattern across 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. An inert chemical tracer (sulphur hexafluoride, SF6) was released into the ACC in early 2009, and subsequent cruises measured temporal changes in the tracer distribution via the analysis of water samples collected at CTD stations. In addition, a mooring cluster was deployed in Drake Passage in early 2009 provided approximately two years' worth of hydrographic time series data. Floats and drifters were also deployed in the 2009 and 2010 seasons. The DIMES project aims to enhance understanding of mixing processes in the Southern Ocean, as it is thought that such processes may significantly affect ocean energetics and property balances, and thus have implications for the accuracy of climate models. DIMES brings together researchers from both UK and US institutions, including the National Oceanography Centre (NOC), the University of East Anglia (UEA), British Antarctic Survey (BAS), the Scottish Association for Marine Science (SAMS), Woods Hole Oceanographic Institution (WHOI), Scripps Institute of Oceanography, Florida State University, the University of Washington and Massachusetts Institute of Technology (MIT). The UK principal investigator (PI) is A. Naveira Garabato from NOC and the UK data will be managed by the British Oceanographic Data Centre (BODC). Data collected on US cruises, including all float and drifter data, will be managed by US institutions and are not held at BODC.