As a key region of the global thermohaline circulation, the Denmark Strait between Iceland and Greenland is the pathway for the densest component of the North Atlantic Deep Water, the Denmark Strait Overflow Water (DSOW).Since 1999, it has been probed with acoustic instruments in the SFB 460 program lead by the Institut für Meereskunde Kiel. The data from bottom Pressure/ Inverted Echo Sounders (PIES) and ADCP current profilers, deployed in a model-optimized mooring array at the Denmark Strait sill, resolve both spatial and temporal variability of the overflow.After recovery of moorings in August 2002, the time series available have a total length of 27 months. The data allow for transport estimates based on direct ADCP measurements and integrating geostrophic PIES observations. Including model comparisons, a mean DSOW transport of 3.0 Sv is calculated with an accuracy of ±0.1 Sv. A statistical analysis with autoregressive moving average models has improved the information about integral time scales and dominant frequencies of the overflow variability.Until now, estimates of the mean DSOW throughflow have been remarkably stable. The PIES observations show a close correlation between sea surface height anomalies and the DSOW plume thickness. This opens a perspective for long term monitoring by remote sensing with relevance for climate change. First comparisons of in-situ measurements and satellite altimetry are presented.