What does a horizontal motion of a white light or flare signify?

A horizontal motion of a white light or flare usually indicates a specific and urgent maritime signal. In navigation and safety at sea, such signals often communicate a request for attention or an alert regarding a hazardous condition. It is widely understood among mariners that a horizontal white light or flare signals that the area is highly dangerous, and it is crucial for vessels to avoid it or proceed with extreme caution.

Depending on the context of maritime communication, different signals might convey various statuses or conditions, but a horizontal motion specifically denotes a serious concern regarding navigational safety. In this instance, the correct interpretation emphasizes the need for caution and awareness of potential hazards in the vicinity, making it critical for mariners to heed these signals properly.