Examples of these illustrations from the Wendt Map Collection are on display in Columbia River Maritime Museum’s “Mapping the Coast” exhibit.

What did the world look like 400 years ago? For many cartographers of the time, it was difficult to say.

Vast swatches of the world — including North America — remained undocumented in European written records.

Life at sea was exceptionally dangerous prior to modern technology that made maritime spaces more navigable.

Throughout the medieval and Renaissance periods, many disasters at sea were explained by monsters below the surface that terrorized traveling ships.

Depictions of the monsters in question varied widely. While some illustrations showed mythical, serpentine beasts; others were of whales, walruses or other marine mammals more familiar today.

For many in medieval Europe, the existence of a whale was terrifying in and of itself. “Old salt” mythology describes sailing ships unknowingly anchoring and making camp on a whale’s back, only to be dragged to the depths of the sea as the whale escaped them.

There was also a common belief at the time that land animals all had an aquatic equivalent.

Sea cows, sea dogs and sea lions were all fair game in early depictions of marine life — typically their land-based counterpart with fish tails. While it seems outlandish to us today, many cartographers were drawing on the scientific authorities of the day.

Some historians believe that the illustrations were not meant to literally depict creatures of the deep, but instead symbolized the unknown perils of traveling at sea.

Author Chet Van Duzer writes, “I would suggest that sea monsters on maps have two main roles. First, they may serve as graphic records of literature about sea monsters, indications of possible danger to sailors … Second, they may function as decorative elements … suggesting in a general way that the sea can be dangerous, but more emphatically indicating and drawing attention to the vitality of the oceans … and to the cartographer’s artistic talents.”

Van Duzer also notes that not all maps of this period had sea monsters.

Given that they were considered decorative by most, illustrations of sea monsters were something a client would have to specifically request from the mapmaker.

The only people who could afford this at that time would have been royalty or other nobility — ironically, working sea captains and their crews rarely had such detailed maps with them.

The lore that surrounded these creatures created a prime market for the unsuspecting consumer.

Historian James B. Sweeney describes “Jenny Hanivers,” or dried skates posed as the dead offspring of mermaids.

Other animals, like frogs and snakes, were dried and manipulated to pass as a mysterious monster harvested from the ocean. A layman customer at that time may not have realized they were being swindled.

By the early 18th century, monsters on maps became less and less common. With the dawn of the Enlightenment period and new scientific exploration, images of sea creatures became more realistic.

These maps live on as reminders of the power of the oceans and the many mysteries that still lie within them.