Description: Three high resolution multicore records have been collected at three sites in the western Mediterranean with a MC400-Multicorer system during the MedSeA cruise (Mediterranean Sea Acidification in a changing climate) on 2 May to 2 June 2013 onboard the R/V Angeles Álvarino. Core MedSeA-S3-c1 was retrieved in the Alboran basin (Lat. 36.0746° N, Long. 04.11040° W) at a water depth of 1137 m, with a core length of 33 cm. Core MedSeA-S23-c1 was recovered at a water depth of 1156 m in the Balearic basin offshore Barcelona (Lat. 41.1121° N, Long. 2.38200° E) with a core length of 43 cm. MedSeA-S7-c2 was collected at the Strait of Sicily (Lat. 37.7080° N, Long. 12.40553° E) at a water depth of 263 m, with a core length of 46.5 cm. All three cores have been analyzed for changes in size normalized weight (SNW) and stable carbon isotopes (δ13C), measured in planktic foraminiferal clacite shells of the two species Globigerina bulloides and Globigerinoides elongatus. Boron (δ11B) isotopes have been measured in tests of Globigerinoides elongatus at the Alboran site, and in Globigerinoides ruber albus at the Strait of Sicily. Complementary data for the Strait of Sicily record has been obtained, including a 210Pb based age depth model, sea surface temperatures (SST), alkenone concentrations and planktic foraminiferal assemblage changes. The Strait of Sicily record (MedSeA-S7-c2) covers around the last 200 a, describing environmental changes throughout the Industrial Era (IE) at high temporal resolution. The Alboran (MedSeA-S3-c1) and Balearic Sea (MedSeA-S23-c1) records spanning the last about 1 ka at lower temporal resolution, displaying oceanographic changes throughout the transition from the pre-industrial era to present, as discussed in (Pallacks et al., 2021; doi:10.1016/j.gloplacha.2021.103549). Data has been collected to investigate the response of marine calcifiers to the combined effects of climate change stressors on decadal to centennial timescales, caused by anthropogenic CO2 emissions.