In the summer of 1966 (1966-06-20 to 1966-07-08), during approximately one month, research vessels from Finland, Germany, Norway, Sweden and UK-Scotland made hydrographical investigations in the Skagerrak, parts of the NE North Sea Proper and N Kattegat. Germany also deployed recording current meters, 16 instruments at 10 positions, with some 20 days' data collection. Finally, there were current measurements from research vessels drifting or at anchor. One of the aims was to estimate the average water transport and its origin. The data has been quality controlled.