Dissolved oxygen concentrations in the oceans have been decreasing over the past several decades, but the causes and consequences of this deoxygenation remain poorly understood. Ocean oxygen loss directly impacts ecosystems through changes in food web structure and biodiversity. Under low oxygen conditions, less energy is available to higher trophic levels, and a variety of microbial processes act to decrease oceanic nutrient inventories, while producing climate-active trace gases including nitrous oxide and methane. Current research efforts are defining the networks underlying microbial metabolism in low oxygen waters, but many open questions remain regarding the future oxygenation status of the ocean, and ecological responses at the individual, population and community levels. This workshop brings together leading experts on the biogeochemistry, oceanography, and ecology of the northeastern Subarctic Pacific Ocean to review current data and knowledge on deoxygenation. The workshop aims to develop more coherent geological and paleoclimate perspectives, and to discuss potential future trajectories and impacts of ocean oxygen loss.