I love looking at ancient maps. Even those that are relatively correct feature fantastic artwork in the spaces that would otherwise have no information. But some of those extra decorations had a purpose.
The richly decorated Carta Marina, from 1539 might seem a little crude by today’s standards but modern satellite imaging revealed that the sea monsters shown in parts of the ocean on the map actually correspond to well known storm fronts, dangerous currents and maritime hazards. This was perhaps just a method of depicting this at the time, as a warning to sailors venturing into these areas
This picture is just a small detail of the Carta Marina. See the full map and many others in a roundup of old maps at Dark Roasted Blend. Link