What are navigation charts on Age of Empires?

In Age of Empires, navigation charts are graphical representations of water bodies on the game map, showing the layout of rivers, seas, and oceans. They provide players with crucial information about where naval units can travel, as well as identifying strategic locations for trade and combat. Players can use these charts to plan their naval strategies effectively and navigate their fleets across the map. Understanding navigation charts is key to mastering water-based gameplay in the series.