Hydrographic data from the Kara Sea show significant storage of freshwater (∼2.5 years of river input). This provides a buffer against large changes in ice and hydrographic conditions that might otherwise result from an anomalous year's runoff. The distribution of freshwater in the Kara Sea closely corresponds to bottom contours, indicating strong bathymetric influence on the spreading pattern. Observations also indicate areas within the Kara Sea in which the upward flux of sensible heat influences the thickness and the extent of ice coverage. Warm, saline Atlantic water which flows into the Kara Sea is particularly important in this regard. However, there is evidence that the flow of Atlantic water bifurcates in the northern reaches of the Kara Sea, so that one portion continues southward while the other curves back and exits with relatively little local heat loss.