This dataset includes measurements of opal (wt %), total organic carbon (mg C/g dry sediment), total nitrogen (mg N/g dry sediment), bulk nitrogen isotopic composition (d15Nbulk), and diatom-bound nitrogen isotopic composition (d15Ndb) from 36 samples from ODP sediment core 1098B-5H-7 on the western Antarctic Peninsula. The sediments were deposited during a period of deglaciation about 12.5-12.3 ka.