This dataset consists of measurements of various physical oceanographic parameters collected on a comprehensive survey of the Scotia Sea undertaken from 21 April and 22 May 2015. Data were collected on RRS James Clark Ross cruise JR311. Navigation data were collected using an Applanix POSMV system and meteorology and sea surface hydrography were collected using the NMF Surfmet system. Both systems were run through the duration of the cruise, excepting times for cleaning, entering and leaving port, and while alongside. A CTD was launched at 24 stations throughout the cruise. Moving Vessel Profilers, Seasoar towed CTD, oceanloggers, temperature loggers and MSS turbulence profilers were all towed for multiple sections of the cruise. Multiple temperature-chain loggers were deployed at stations throughout the cruise. JR311 was the research cruise conducted as the observational element of the NERC Standard Grant, Surface Mixed Layer Evolution at Submesoscales (SMILES). The project aims to improve our understanding of submesoscale dynamics in regions characterised by strong fronts and where they impact on water mass transformation. For this reason, the field site was chosen to be the subantarctic front (SAF) to the east of Drake Passage where the Antarctic Circumpolar Current generates a pronounced front between the warmer subantarctic water to the north and the subpolar water to the south. To the north of the SAF, subantarctic mode water is formed through a process previously considered to be governed by air-sea interaction alone. SMILES aimed to investigate the extent to which submesoscale dynamics at the SAF and the surrounding region may impact on, and potentially govern, this process of water mass transformation. The Discovery Science project was led by Standard Grant reference NE/J009857/1, with child grants NE/J010472/1, NE/J010367/1 and NE/J008214/1. NE/J009857/1 was held at the University of Plymouth, School of Engineering, led by Dr. Phil Hosegood, running from 01 July 2014 to 31 December 2017. NE/J010472/1 was held at the University of Cambridge, School of Applied Maths and Theoretical Physics, led by Dr John Ryan Taylor, running from 01 April 2013 to 30 September 2016. NE/J010367/1 was held at the Plymouth Marine Laboratory, led by Dr Ricardo Torres, running from 01 June 2014 to 30 June 2017. Finally, NE/J008214/1 was held at the NERC British Antarctic Survey, led by Professor Michael Meredith, running from 01 July 2013 to 31 October 2016. All data have been received by BODC as raw files from the RRS James Cook to be processed and quality controlled using in-house BODC procedures and made available online. Data are available as raw files on request.