What does it mean when a boat displays three vertical black balls?

When a boat displays three vertical black balls, it indicates that the vessel is aground. This visual signal is recognized internationally and is part of the navigation rules designed to keep other vessels informed about the status of another boat. The display of three vertical black balls serves as a warning to nearby boaters that the vessel is not navigating and is positioned in a way that may obstruct navigation or pose a hazard. Monitoring such signals is vital for safe boating practices, as it helps prevent collisions and ensures effective navigation in busy waterways.