As part of the onshore science party in IODP Expedition 347: Baltic Sea Paleoenvironment, we are sequencing single cell genomes of uncultured archaea and bacteria in sediments as deep as 85 m. The vast majority of the microbial diversity in deep subsurface environments has eluded efforts to be cultured. Single cell genomics affords us the opportunity to uncover new prospective ecophysiological roles carried out by enigmatic yet abundant organisms. We now have 40 single amplified genomes (SAGs) from 37.5 mbsf and 20 SAGs from 85 mbsf at Baltic Sea Basin hole 60B. The SAGs include members of the deeply-branching archaeal and bacterial groups lacking cultured representatives. To our knowledge, these are the first SAGs ever successfully obtained from deep (> 10 mbsf) marine sediments. We currently have funding to sequence 10 SAGs. Adding 3 more would therefore greatly expand our understanding of the genetic composition of uncultured microorganisms in deep Baltic Sea sediments.