This dataset consists of measurements of density, electrical conductivity, sound velocity and travel time, salinity, depth and temperature of the water column. The data were acquired from the RV Falcon Spirit, the Plymouth University vessel. The small 14m catamaran was used daily from 13 May 2012 to 24 May 2012 in the Celtic Sea, off the Cornish coast, with the idea to capture high-quality, spatially-resolved field data ahead of the Wave Hub construction. Measurements were collected using CTDs, moored temperature loggers, ADCP, VMADCP and towed minibat CTD. These cruises formed the field component of NERC Discovery Science project "Wave Hub baseline study". The aims of the research were to obtain a detailed oceanographic study at the Wave Hub site and surrounds - covering the whole range of physical, chemical and biological parameters before the deployment of Wave Hub infrastructure and wave energy devices – and to ensure data acquisition in time and space to allow development of physical and ecosystem models at scales relevant to wave arrays. Ultimately models will make predictive assessments of the extent, timescales and intensity of ecosystem impacts and perturbation resulting from implementation of wave energy arrays. Other aims include: engagement of environmental economists to ensure the data can be used to develop economic valuation estimates of critical life-supporting ecosystem services at scales appropriate to arrays of wave devices for comparison with other uses of marine space and to address questions that have arisen directly in respect of marine renewable energy development and sustainable use of marine resources. The Discovery Science project was composed of Standard Grant reference NE/I015094/1 as the lead grant with child grants NE/I015183/1 and NE/I015108/1. The lead grant, NE/I015094/1, ran from 01 August 2010 to 31 July 2012, with Dr Ricardo Javier Torres, Plymouth Marine Laboratory, as principal investigator. The child grant NE/I015183/1 ran from 01 August 2010 to 31 July 2011, led by Professor Michael Richard Belmont, University of Exeter. The second child grant, NE/I015108/1, ran from 03 December 2010 to 31 July 2012, led by Dr Philip John Hosegood, University of Plymouth. All data detailed here were received by BODC as raw files from the RV Falcon, processed and quality controlled using in-house BODC procedures. Towed undulator CTD data and temperature logger data have been processed to completion and are available online on the BODC website. The remaining data will be made available in the near future.