Underwater glider data from the MASSMO-5 project collected in the North and Nordic Seas (2018-19) dataset https://portal.medin.org.uk/portal/start.php?tpc=006_d96ccd1a004250eeb0e0c43bf3181554 The MASSMO 5 dataset includes the near real time transmitted EGO (Everyone’s Gliding Observatories) NetCDF versions of glider data collected by five submarine gliders across three deployment campaigns. Recovery versions of data downloaded from the all gliders with no quality assurance are also available on request. Glider sensor suites included CTD, bio-optics, and oxygen optodes. Parameters observed include, temperature, salinity, chlorophyll fluorescence, optical backscatter, and oxygen data. The MASSMO 5a mission focused on the period 23 Jun 2018 to 06 Jul 2018 and included three submarine glider deployments (UK glider deployments only are included in this dataset). All assets were deployed from NRV Alliance in partnership with NATO-CMRE, but were recovered prematurely due to vessel technical issues. The primary geographic focus of MASSMO 5 was the outer shelf and upper slope off northern Norway, in the region between Bear Island and southern Spitsbergen, but outside the 12 mile territorial limits of these islands. The MASSMO 5b mission occurred within the period 17-24 Oct 2018, a total of three ocean gliders were deployed. The primary geographic focus of MASSMO5b was the northern North Sea to the east of the Orkney archipelago. The MASSMO 5c mission was aborted and no data were collected. The MASSMO 5d mission occurred within period 26 Apr 2019 to 6 May 2019, there was deployment of a single ocean glider. The primary geographic focus of MASSMO 5d was the Faroe Shetland Channel. MASSMO 5 was co-ordinated by the National Oceanography Centre (NOC) in partnership with University of East Anglia (UEA), Plymouth Marine Laboratory (PML) and Scottish Association for Marine Science (SAMS). The mission was sponsored by Defence Science and Technology Laboratory (DSTL) and involved close co-operation with the NATO Centre for Maritime Research and Experimentation (CMRE) and UK Royal Navy, and was supported by several additional commercial, government and research partners. 20220302 20190905