Seawater salinity and oxygen isotopes along the U.S. East Coast from 24 °N to 44 °N

Oxygen isotope measurements of seawater (δ 18 O w ) are an important tool in the study of climate, oceanography, and hydrology, both today and in the past. δ 18 O w and salinity are controlled by similar hydrologic processes, but δ 18 O w is more readily recorded in geologic materials than salinity and is thus more accessible for paleoceanographic reconstructions. Modern instrumental δ 18 O w data exist, but these data can be sparse in certain regions and/or sporadically collected through time - some predating modern instrumentation and current standardization practices. In this dataset, we present 364 new paired salinity and δ 18 O w measurements from seawater samples collected along the U.S. Eastern Seaboard, nearly tripling the existing data in this region and dramatically improving spatial coverage. By collecting δ 18 O w at such a high spatial resolution, this dataset expands the utility of δ 18 O w as a tracer for both modern oceanography and paleoceanography, provides valuable insights into nearshore hydrologic processes and basin-scale ocean dynamics, and offers a robust foundation for more integrated studies of ocean circulation and water-mass properties.