This dataset consists of measurements of water column structure including hydrographic profiles, temperature and salinity, turbulence data, turbidity and fluorescence profiles, current velocities and sound velocities. The measurements were undertaken during a comprehensive survey of the southern Celtic Sea between May and August 2012. Some turbulence microstructure data were collected from the 14th to the 24th of May 2012, while the remaining data were collected from the 10th to the 22nd of August 2012, with the use of the RV Falcon Spirit. These cruises formed the field component of NERC Discovery Science project "Assessing the sensitivity of marginally stratified shelf seas within a changing climate". The data were collected in order to identify processes involved in the existence and intensity of the front displays not governed by tidal periodicities, to test whether the processes identified as important to changes in shelf sea stratification through in-situ measurements are indeed responsible for observed changes and to incorporate knew knowledge into state of the art numerical models that can up-scale the processes observed within this project to the shelf sea environment. The Discovery Science project was composed of Standard Grant reference NE/I001832/1. The project ran from 01 January 2011 to 30 June 2014. Dr Philip Hosegood of University of Plymouth School of Marine Science and Engineering was the principal investigator of this project. The moored temperature logger data have been received by BODC as raw files from the RV Falcon Spirit, processed and quality controlled using in-house BODC procedures and can be downloaded on-line from the BODC website in a variety of data formats including ASCII, ODV and NetCDF. Full documentation on the dataset is supplied on download. Raw file versions of the minibat towed undulator transect data, moored ADCP data, VMADCP data and turbulence microstructure data are available on request.