Information: Squares provide information such as places to find food, supplies, and repairs; and they give directions, distances, and other non-regulatory information.
Danger Area: Diamonds warn of dangers such as rocks, shoals, construction, dams, or stumps. Always proceed with caution and keep a safe distance. Never assume that every hazard will be marked by a buoy.
Controlled Area: Circles indicate a controlled area such as no wake, idle speed, speed limit, or ski zone.
Exclusion Area: Crossed diamonds indicate areas off limits to all boats, such as swimming areas, dams, and spillways.