In 1596 Jan Huygen van Linschoten published his Itinerario. It contained a section called the Reys-gheschrift, which was the first nautical compendium to include sailing routes on the earth’s three main oceans. This publication enabled the Dutch and the English to launch successful maritime strategies. In this article I discuss how Iberian Science, mainly its sources, was employed in the Reys-gheschrift, as well as the major changes made prior to publication and the reasons why Linschoten introduced them. These topics are connected with a major debate concerning the drive for geographical knowledge, in which I attempt to demonstrate the importance of Iberian Science for the onset of the Dutch maritime expansion and for European seamanship more broadly in the sixteenth and seventeenth centuries.