The Greenland Sea is one of the few major areas where convective renewal of intermediate and deep waters contributes to world ocean ventilation. Basin-scale cyclonic circulation, boundary currents advecting waters of Atlantic and Polar origin, mixing across the fronts related to the boundary currents, wintertime heat loss to the atmosphere, ice formation and related brine release and sequences of penetrative plumes control the renewal. The scales involved range from gyrescale to small-scale and from interannual to hours. This wide range of environmental conditions provides an extreme ecosystem for which biota have evolved specific surviving strategies. In a joint effort, research groups from 11 nations are investigating both the processes and the rates of water-mass transformation and transport and are working on the food chain dynamics and the life cycles of dominant species up to the zooplankton level in a several-year program—the Greenland Sea Project (GSP).