Maps often explain location in terms of unchanging landmarks, like mountains or streets, but they can also be used to navigate using changing phenomenon, like sea and weather conditions. Explorers from the Micronesian Pacific islands navigated through the use of stick charts, which identified patterns in ocean conditions such as swells, waves, or wind (SF Fig. 8.2 A). The stick chart was constructed of materials like palm ribs, coconut fiber, and shells or coral pebbles. The curved palm ribs represented swells; shells or coral pebbles were used to represent islands. The connections between the sticks showed oceanic patterns such as the direction of swells, the way swells curved around islands, and how swells interacted with one another (e.g., SF Fig. 8.2 B). It is important to note that because these charts where not made to represent exact distances between islands, stick charts for the same islands can vary greatly. In addition, because they were meant to be used and interpreted by the navigator who constructed them, stick charts are variable in their design. Furthermore, unlike traditional maps, it is believed that navigational aids were not brought on trips but rather memorized beforehand or used as teaching aids.