Polynyas are relatively ice-free regions when compared to the areas around them, and have been suggested as being foci for energy transfer between the atmosphere and ocean, ice “factories?, and critical areas with respect to polar ecosystems and biogeochemical cycles. This volume presents an integrated, multidisciplinary review of polynyas in both the Arctic and Antarctic. It emphasizes the meteorology, ice dynamics, oceanography, biological components, chemistry, and modeling of these systems, particularly with respect to their roles in polar processes and distributions. The various interactions within polynyas, particularly between the physical forcing and biological responses, is emphasized, as are the potential changes in polynyas that might occur under a climate regime that is rapidly changing. The authors of the reviews are leaders among their respective countries in polynya research, and all are internationally recognized.