What does a square sign with a black cross mean?

A square sign featuring a black cross indicates "No entry." This sign serves to alert boaters and individuals that they are not permitted to enter a specific area. Such restrictions can be in place for various reasons, including safety measures, environmental protection, or access control. The design of a black cross is universally recognized as a clear indicator that entry is prohibited, helping to maintain safety on the water and protect designated areas for other uses or conservation efforts.

Understanding this sign is crucial for boating safety and compliance with regulations that aim to protect both people and the environment. It's important to recognize these symbols while on the water to avoid potential hazards or legal repercussions related to restricted areas.