Polynesian Stick Charts

The peoples of the Polynesian islands traveled to and colonized the islands of the Pacific centuries ago, and maintained a common culture by traveling between islands on canoes. How did these peoples manage to depart the safe shores and travel between the many islands safely?

It turns out that simple yet accurate charts made of sticks have long been used by the Polynesians to map islands, currents, and sea swells. These charts came in different types, and the information was closely guarded as secrets. Although the maps appear primitive, the stick charts are a significant contribution to the history of cartography because they represent the first system of mapping ocean swells.

You can read more information here, here and here. Most interestingly, this article explains how the maps can be read.