What does continuous sounding of a fog wistle by a vessel indicate?

Continuous sounding of a fog whistle by a vessel indicates that the vessel is either at anchor or making way through foggy conditions. This sound serves as a warning to other vessels in the vicinity, helping to prevent collisions by alerting them to the presence and location of the ship. The fog whistle is part of the International Regulations for Preventing Collisions at Sea (COLREGs), which mandates specific sound signals for vessels operating in restricted visibility.