The North Water Polynya (NOW) is a polynya (area of year-round open water surrounded by sea ice) that lies between Greenland and Canada in northern Baffin Bay. The world's largest Arctic polynya at about , it creates a warm microclimate that provides a refuge for narwhal, beluga, walrus, and bowhead whales to feed and rest. While thin ice forms in some areas, the polynya is kept open by wind, tides and an ice bridge on its northern edge. Named the “North Water” by 19th century whalers who relied on it for spring passage, this polynya is one of the most biologically productive marine areas in the Arctic Ocean.