This dataset comprises physical, chemical and biological oceanographic measurements collected from the Mid-Atlantic Ridge as part of the UK 'RidgeMix' project between 2015 and 2016. Physical measurements include water column profiles of temperature, conductivity, current speed/direction and turbulence. These are supplemented by i) chemical samples targeting inorganic nutrients, oxygen and isotopes of radium/nitrate, ii) biological samples to understand plankton distribution and to determine chlorophyll and enzyme concentrations. Samples were collected from the water column above the Mid-Atlantic Ridge, between latitudes of approximately 23 and 39 degrees North. Sampling commenced in September 2015 with the deployment of moored sensors (thermistors, MicroCATs and ADCPs). This was followed up with a dedicated research cruise (JR15007) between May and July 2016. During this cruise standard observational measurements were undertaken (including CTD, LADCP, SADCP and discrete water sampling), together with more specialised data collection activities (including deployment of turbulence profilers, standalone pumps, zooplankton nets, ocean gliders and a drifting wirewalker mooring). The cruise was also used to recover the moored instruments deployed the previous year. RidgeMix aims to investigate the mixing from internal tides over ridges and seamounts and the biogeochemical implications of this. The project is funded by a Responsive Mode grant from the UK Natural Environment Research Council (NERC) and ran from 2014 until 2019. RidgeMix was led by Professor Jonathan Sharples from the University of Liverpool, in collaboration with Principal Investigators from the National Oceanography Centre (Dr Matthew Palmer) and University of Southampton (Professor Alberto Naveira Garabato). This dataset collection brings together the observational component of RidgeMix. Users are advised to contact Principal Investigators for access to associated ocean modelling output from the project. Assembly of the observational dataset is still ongoing with BODC currently holding CTD and discrete sample data (chlorophyll and dissolved inorganic nutrients).