At night, what signal is used by a lifesaving station to indicate "landing here is highly dangerous"?

The correct signal used by a lifesaving station at night to indicate that "landing here is highly dangerous" is the horizontal motion of a white flag or flare. This signal is widely recognized in maritime safety protocols, as it conveys a clear and immediate warning to mariners regarding hazardous conditions.

The horizontal motion implies urgency and visibility, making it an effective means of communication in low-light scenarios. The choice of a white flag or flare also serves a dual purpose: it is easily distinguishable against the night sky and does not suggest a safe passage.

In comparison, other signals may not effectively communicate the same level of danger or could be confused with other meanings. For example, a vertical motion of a red flag typically indicates a warning but does not have the same universal acknowledgment for nighttime hazards. Similarly, a sustained blue light is often associated with rescue operations rather than a warning against landing. Flashing a yellow lantern, while possibly indicating caution, does not carry the same established significance as the white signal in indicating immediate danger.