he Reykjanes Ridge is a major topographic feature of the North-Atlantic Ocean. It lies in a central position along the main paths followed by the upper and lower limbs of the Meridional Overturning Cell (MOC), which contributes at moderating the European climate in creating a transport of heat toward the North Atlantic. Our hypothesis is that the Reykjanes Ridge influences the main components of the upper and lower limbs of the MOC because it is a strong constraint on the horizontal and vertical circulation, it impacts the water mass distribution and evolution and it is a region of intense turbulent mixing. The objective of the RREX project is to conduct a process study in order to better understand the role of the Reykjanes Ridge on the dynamics and water mass transformation in the subpolar gyre and ultimately on the MOC. This project relied on two hydrographic cruises carried out in 2015 and 2017 to acquire the adequate dataset to (1) provide a synoptic high-resolution and full depth survey to monitor the flow along and across the ridge, (2) to quantify the variability of the vertical and horizontal structure of the currents parallel to the ridge at daily to seasonal time-scales and (3) to provide sufficient turbulence observations to monitor the heterogeneous and intermittent mixing processes.  This dataset gathers discrete measurements of pH, dissolved inorganic nutrients (nitrate, phosphate and silicate) and hydrographic variables (salinity, temperature, dissolved oxygen) obtained during the cruise RREX 2015 (Reykjanes Ridge Experiment) carried out in the North Atlantic Ocean from 5 June to 10 July 2015 aboard R/V Thalassa