This dataset comprises a time series of measurements of water current, temperature, conductivity, and pressure from instruments deployed at various depths in the Orkney Passage from 2007 onwards. The instruments were deployed in sub surface oceanographic moorings at fixed locations, in order to monitor the transport of Weddell Sea Deep Water (ESDW), a precursor to Antarctic Bottom Water (AABW), flowing northward from the Weddell Sea into the Scotia Sea. For 2007-2011 data are typically at hourly resolution; in subsequent years, most instruments are sampling at 10 minutes' resolution. The moorings are deployed in water depths ranging between approx. 1750 and 3670 metres, with instrument depths between 1250 and 3660 metres. This time series originally started out as part of the British Antarctic Survey's Long-Term Monitoring and Survey (LTMS) programme, led by Keith Nicholls; from 2016 it is continuing as part of the Ocean Regulation of Climate by Heat and Carbon Sequestration and Transports (ORCHESTRA) project, led by Emily Shuckburgh (British Antarctic Survey) and Dynamics of the Orkney Passage Outflow (DyNOPO) led by Alberto Naveira Garabato (National Oceanography Centre). Additional support for mooring instrumentation has come from NOAA through their Ocean Climate Observation Program, Weddell Sea Moorings project, PI's Bruce Huber and Arnold Gordon, Lamont-Doherty Earth Observatory, Columbia University. The mooring work is currently led and coordinated by Povl Abrahamsen at the British Antarctic Survey. The data are subject to a two year organisational moratorium from collection after which they become publically available.