Deals with the mesoscale variability of water masses in the Greenland Sea and its implications for bottom water formation. The same section in the central Greenland Basin was sampled in 1989 and 1990; an additional transect across Fram Strait was carried out in 1990. The data set reveals a surprisingly strong horizontal variability of space scales between 20 and 60 km in the entire Greenland Sea, not only in the frontal zones. The area investigated is subdivided into four hydrographical regimes for which mesoscale variability is discussed in detail. A noteworthy result is the major change of the deep sea thermal structure within 1 year. -from Authors