BODC PROJECT DOCUMENT NO. 28556 Applies to BODC Series Ref. Nos.: 34174, 34186, 34198, 34205, 34217, 34229 IOS North Sea Experiment 1981 An experiment was carried out by I.O.S. Bidston in the North Sea during May and June 1981. The scientific objectives were (i) to investigate the slope of the mean sea level surface between Leith and Immingham, (ii) to study the tidal energy budget in a shallow coastal region and (iii) to measure currents around a sandbank to test theories of spring neap changes in the mean currents. 24 rigs containing recording current meters, thermistor chains or pressure recorders were deployed for 40 days at 15 stations. Data from nearby coastal tide gauges were also used. The density field was measured during both the deployment and recovery legs by continuous monitoring of sea surface temperature and conductivity and by recording CTD profiles.