Portugal, in a strategic geographical location in between the Antique Mediterranean world and the Northern Seas, was a collector of information (real stories, epic tales, and local myths) both from the North and the South. The aim of the present paper is to understand if knowledge about large animals of the marine realm from Northern Europe was received in some Southern European early modern nations, particularly in Iberia. In these regions the contact with real marine life prevailed through fisheries and whaling, as well as due to strandings and other rare observations from nature, which allowed the construction of narratives about large whales, its symbolic and ordinary importance, as about different types of sea monsters (including mermaids, tritons, nereids and water nymphs). Whales, the biblical Leviathan, was a paradigmatic example of such and was present in the texts, cartography and other iconography, from late medieval and early modern Portuguese authors. These large animals fell inevitably in the category of sea monsters, as they were strange-looking, frightening and associated with dangerous or harmful events. But despite this, and overriding these characteristics, they were edible and their sub-products were useful so they would be hunted and consumed. The whale was, in fact, the archetype of the large sea monster, simultaneously mythical and mundane. So, all these marine beings, most of the time a mixture of real and fantastic events and features, were subjects of the interest of humanists and scholars, natural philosophers and historians. Here, the analysis of documental and visual sources will be conducted in order to understand the real animals described versus the fantastic beings present. Works by the Portuguese writters Damião de Góis and Luis de Camões; cartography pieces by Diego Gutiérrez, Álvaro Secco or Luis Teixeira; as well as different oil paintings and illustrations will be considered. These will be compared with information from Aristotle and Pliny, as well as with the works of Olaus Magnus, Sebastian Munster and Adriean Coenen. Common characteristics, or clear differences, in written descriptions and visual depictions of whales and other marine mammals will be analysed in order to obtain a sense of the reception of knowledge about the sea from outside in Iberia. Were early modern Portuguese authors really modern or were they relying in previous sources of information and knowledge? Did a local coastal contact with marine life existed and is it reflected in their cultural productions? How modern and Southern were the whales known and represented by Portuguese in Iberia?