In 1995, the first of a nearly continuous sequence of biophysical moorings was deployed at a site (M2) on the southeastern Bering Sea shelf. Over the next 15 years, 10 additional mooring sites were initiated. The resultant long-term biophysical mooring array extends over 1,800 km from the southern Bering Sea to the northern Chukchi Sea, covering most of the US Arctic. It provides a full range of oceanographic data for researchers, stakeholders, and managers. In addition, these data sets have been critical for the validation of regional ocean models. The ocean temperature data have quantified regional warming and formed the basis for understanding how warmer temperatures and loss of sea ice are modifying these high-latitude marine ecosystems. Changes observed in the context of observations from the mooring program include delayed spring bloom, low abundances of large crustacean zooplankton and crab species, seabird die-offs, changes in ocean acidification, northward expansion of subarctic fish species, and shifts in the ranges of marine mammal species.