A simple Lagrangian transport model was applied to obtain estimates of transport routes of conservative passive tracers in the North Sea. A vertically integrated time-dependent flow field derived from the daily output of a three-dimensional baroclinic circulation model was used in the transport model. The simulation period covers the years from 1969 to 1982. The calculations were carried out in order to get estimates of both, the low-frequency flow in the North Sea and the resulting dispersion of matter within the sea. Point sources are assumed which release tracers continuously and with a constant rate. Hence the variability of the flow field can be visualized by the temporal and spatial fate of the released tracer ensemble. The model results are displayed in three different ways to provide a comprehensive description of the complex spacetime character of the system.