The Ocean Observatories Initiative (OOI) Endurance Array in the Northeast Pacific off the coasts of Oregon and Washington is designed to measure changes in the ocean on timescales from hours to decades. The Endurance Array is located halfway between the pole and the equator in one of the major coastal upwelling systems on our planet, the California Current System. This area is forced locally by winds, waves, tides, and freshwater inputs from rivers and, more broadly, by large-scale ocean-atmosphere phenomena from both the south, for example, the El Niño-Southern Oscillation, and the north, for example, changes originating in the subarctic Gulf of Alaska. The Endurance Array spans the continental shelf and slope and hosts a variety of platforms and sensors for measuring physical-biogeochemical oceanographic processes. After briefly introducing the unique OOI platforms and range of sensors that make up the Endurance Array, we describe three phenomena with durations spanning hours to years. These include an ocean response to the total eclipse of the Sun on August 21, 2017, the devastating effects of a low-oxygen event off central Oregon, and the appearance of an anomalously warm upper-ocean feature off the Pacific Northwest in recent years.

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