The Dynamics of Orkney Passage Outflow (DynOPO) project data set comprises physical oceanographic and hydrographic data, including measurements of turbulence, temperature, salinity and currents, complemented by bathymetric and meteorological data. Data were collected within the Orkney Passage by means of moorings and ship-launched instrumentation. RRS James Clark Ross cruise JR20150309 (JR310 & JR272D) ran from 09 March to 14 April 2015. It was not explicitly a DynOPO cruise, rather it undertook the deployment of a mooring for the project. Moorings were deployed in groups of 5 on CTD casts. RRS James Clark Ross cruise JR16005 ran from 17 March to 08 May 2017 and was the primary fieldwork element of the DynOPO project. The cruise had two main goals: (1) to conduct measurements of the hydrographic properties, velocity and turbulent processes of the Antarctic Bottom Water outflow along its pathway through the Orkney Passage region; and (2) to turn around a set of long-term moorings deployed in the area by British Antarctic Survey (BAS) and Lamont-Doherty Earth Observatory (LDEO) scientists, including recovery of additional instruments on some of the moorings deployed by DynOPO 2 years previously. 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. The project received funding under NERC Standard Grants NE/K013181/1 and NE/K012843/1. The lead grant, NE/K013181/1, received funding between 31 March 2015 and 29 February 2020 and was led by Professor Alberto Naveira Garabato (University of Southampton, School of ocean and Earth Science). Grant NE/K013181/1 received funding between 01 October 2014 and 30 November 2018 and was led by Professor Michael Meredith (NERC British Antarctic Survey, Science Programmes). Mooring data collected for the DynOPO project are a component of a long term time series, in association with the Ocean Regulation of Climate by Heat and Carbon Sequestration and Transports (ORCHESTRA) project, led by Emily Shuckburgh (British Antarctic Survey) since 2016. The time series originally started out as part of the British Antarctic Survey's Long-Term Monitoring and Survey (LTMS) programme, led by Keith Nicholls. Information about the time series can be found at https://www.bodc.ac.uk/resources/inventories/edmed/report/6565/ and the ORCHESTRA project https://www.bodc.ac.uk/resources/inventories/edmed/report/6618/ . The majority of the data have been received by the British Oceanographic Data Centre (BODC) as raw files, processed and will be available online in the near future. Remaining data, which will be received in the near future, include: Turbulence, CTD, ADCP, currents, and salinity samples.