The long debates about early medieval geographic knowledge and sailing routes in North Atlantic are based today almost entirely on historical information coupled with results from experimental archaeology. The authors propose herewith a third method, which combines computer simulation with the aforementioned information sources. Geographic information is used to reconstruct the early seascape in a digital environmental simulation that uses also sailing parameters such as bathymetric models (DBMs) of the seafloor, wind, and current relevant to early medieval seafaring in North Atlantic. Both GIS-based and ABM-based modelling tools are used to simulate sea routing in North Atlantic seascapes that linked the Old and the New World together.