Which sound signal indicates a warning or distress?

The sound signal that indicates a warning or distress is signified by five short blasts on a horn. This signal is used internationally to alert others to a situation that may be potentially dangerous or to communicate distress. Such a sound may be used, for instance, when a vessel is in need of assistance or when navigating in congested waters, where a more conventional form of communication might not be effective. Understanding this signal is essential for boating safety and effective communication on the water.

The other sound signals serve different purposes; for instance, a long blast typically indicates a vessel's intention to overtake or that it is leaving a dock, while two short blasts generally indicate that a vessel is altering its course to starboard. Three short blasts are often used to indicate that a vessel is reversing. Thus, recognizing the distinct meaning behind each sound signal is critical for safe navigation and interaction between vessels.