Updated project metadata. Global metaproteomic analyses of microbial biomass from the upper water column of the Central Pacific Ocean. This dataset was used as a discovery dataset to identify peptide biomarkers for cyanobacterial populations for use in targeted metaproteomic calibrated multiple reaction monitoring (MRM) analyses published in in Saito et al., 2014 and 2015. Saito, M. A., McIlvin, M. R., Moran, D. M., Goepfert, T. J., DiTullio, G. R., Post, A. F., and Lamborg, C. H.: Multiple nutrient stresses at intersecting Pacific Ocean biomes detected by protein biomarkers, Science, 345, 1173-1177, 2014. Saito, M. A., Dorsk, A., Post, A. F., McIlvin, M., Rappé, M. S., DiTullio, G., and Moran, D.: Needles in the Blue Sea: Sub‐Species Specificity in Targeted Protein Biomarker Analyses Within the Vast Oceanic Microbial Metaproteome, PROTEOMICS, 15, 3521-3531, 2015.