From the 15th century onwards, when European mariners, explorers, and settlers started in situ observations and descriptions of tropical marine fauna, they were relying on their own eyes, mental preconceptions, as well as previously acquired knowledge. In fact, they had their own mindsets, belief systems, and understandings of the world to cope with. And the same happened with European naturalists, sitting in their offices, writing their encyclopedias, and establishing networks of information. Thus, whales, sharks, rays, or other large animals could easily turn into a terryfing monster of the depths, regardless of whether humans were observing them or writing about them at a distance. Yet, no matter how strange these new animals were to the eyes of European pilots, naturalists, and humanists, they were not strange at all to native peoples bordering Atlantic Ocean.