Slate offers us a beautiful digitally-reproduced map of Renaissance sea monsters. Annotated with creator Olaus Magnus' own writings detailing the terrible beasts, it provides a vivid idea of the perceived dangers of ocean travel in the 16th century. At its printing in 1539, this was the most accurate map of any part of Europe at that time.
The digital reproduction is entertaining. However, one of the illustrations is noted, "Olaus did not say much about the sea rhinoceros, so it is possible that while the other animals were based on tales from seamen, he made this one up."
What!? I have lost complete faith in the veracity of this map.