The flow through the Bering Strait, the only Pacific-Arctic oceanic gateway, has dramatic local, regional, and global impacts. Advanced year-round moored technology quantify challengingly large temporal (sub-daily, seasonal, and interannual) and spatial variability in the ~85km wide, two-channel strait. The typically northward flow, intensified seasonally in the ~10-20km wide, warm, fresh, nutrient-poor Alaskan Coastal Current (ACC) in the east, is otherwise generally homogeneous in velocity throughout the strait, although with higher salinities, nutrients and lower temperatures in the west. Velocity and water properties respond rapidly (including flow reversals) to local wind, likely causing most of the strait's ~two-layer summer structure (by 'spilling' the ACC) and winter water-column homogenization. We identify island-trapped eddy zones in the central strait; changes in sea-ice properties (season-mean thicknesses from <1m to >2m); and increases in annual mean volume, heat, and freshwater fluxes from 2001 to present (2013). Tantalizing first results from year-round bio-optics, nitrate, and ocean acidification sensors indicate significant seasonal and spatial change, possibly driven by the spring bloom. Moored acoustic recorders show large interannual variability in subarctic whale occurrence, related perhaps to water property changes. Substantial daily variability demonstrates the dangers of interpreting section data and the necessity for year-round interdisciplinary time-series measurements.

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We gratefully acknowledge financial support for this work from the NOAA RUSALCA program, the National Science Foundation (NSF) and Office of Naval Research (ONR).