Marine Lexicon is a cooperation project between Portugal and Norway, funded by EEA Grants, aiming at the construction of a thesaurus of European common names of marine mammals (cetaceans, seals and sea lions, and sirenian) and symbolic elements (sea monsters, hybrid beings, folklore creatures) represented in the early modern age (15th-18th centuries). This project established and reinforced Portuguese-Norwegian networking research on historical whaling, sealing, and marine mammals’ appropriation, trade and use from medieval and the early modern period. Documentary and visual sources for the European and Transatlantic Natural History, including saga literature, diaries, treaties, leaflets, maps and travel literatures will be used to dig for past information about local species and names. Artefacts made of parts (bones and other) of the animals, and material from the zooarchaeology/quaternary zoology will be considered too. Words associated with activities of use and extraction, and animal distribution (products, objects, artefacts, toponomy) are also part of the study. We will present the first results to construct an open access online database - the Marine Lexicon - as a new and future tool on the field of marine environmental history, providing a better understanding of the significance of these animals for different societies during this period.