The data set comprises hydrographic data, including salinity, temperature, depth, dissolved oxygen, transmittance and chlorophyll. Chemical and biological measurements of water samples, such as dissolved inorganic nutrients, trace metals (including iron and aluminium), dissolved oxygen, biogenic silica, particulate inorganic/organic carbon and particulate organic nitrogen. Also included are the results of biological experiments focusing on iron and ecosystem grazing pressures. This data set was generated by two research cruises (RRS Discovery cruises D350 and D354) carried out as part of the Irminger Basin Iron Study (IBIS). Data were collected from the Irminger and Iceland Basins on the cruises, which took place between 26/04/2010 and 11/08/2010. Standard cruise measuring techniques, including CTD casts, the ship’s underway system, discrete water sampling and SeaSoar surveys were carried out. In addition, water was collected from an epoxy-coated tow fish and pumped directly into a clean chemistry container using a Teflon pump system through acid washed PVC tubing. Experimental work was performed to measure the biological response to both artificial manipulation of the availability of the micronutrient iron and grazing pressure. Measurement of the uptake rate of various substrates was further performed using a variety of tracer techniques. The study aimed to study the iron biogeochemistry in the high attitude North Atlantic, assess whether community productivity in parts of the North Atlantic is iron limited following the annual spring bloom and determine the factors that lead to this situation. Collectively, the sampling methods adopted as part of IBIS provide a good understanding of the water column structure and the processes taking place within it. The data were collected by scientists at the National Oceanography Centre (NOC) under the supervision of Eric Achterberg. Hydrographic data from the CTDs and underway system (together with associated discrete chemical and biological sample data) are currently held at the data centre. The remaining data described are yet to be supplied.