One short horn blast: This communicates to another ship that you intend to pass it on your port side. Two short horn blasts: This communicates to another ship that you intend to pass on your starboard side. Three short horn blasts: This means that you are operating in reverse, such as backing away from the dock.

In 2026, cruise ship horn signals follow the international COLREGs (International Regulations for Preventing Collisions at Sea) to communicate intentions to other vessels. One short blast (about 1 second) means the ship is altering its course to starboard (right). Two short blasts mean it is turning to port (left). Three short blasts signify the ship is operating its engines in reverse (astern). A single long blast (4-6 seconds) is often used as a warning signal when a ship is about to move or is approaching a "blind" bend in a channel. If you hear five short blasts, it is a signal of danger or doubt, essentially meaning "I do not understand your intentions" or "You are not taking sufficient action to avoid a collision." During poor visibility, such as heavy fog, a ship will sound one long blast every two minutes to alert others of its position. Additionally, many cruise ships use their horns for "ceremonial" purposes, such as playing a few notes of a theme song (like Princess Cruises' Love Boat theme) when departing a famous port like Venice or Miami.