Seeing someone fall overboard at night is a critical, life-threatening emergency that requires immediate and precise action. The first thing you must do is shout "Man Overboard!" as loudly as possible to alert the crew and other passengers. Do not take your eyes off the spot where the person fell; it is incredibly easy to lose a person in the dark, moving water. While keeping your eyes on the person (or the spot), throw a life ring or any buoyant object overboard; even if it doesn't reach them, it serves as a "marker" for the rescuers. If possible, use a high-powered flashlight or "spotlight" to track them. On a cruise ship or large vessel, immediately find the nearest emergency button or use a house phone to call the bridge. The crew will initiate an "Oscar" maneuver (a specific turning pattern) to return to the location. At night, the person's survival depends almost entirely on the speed of the initial response and the ability of a witness to provide a constant "visual bearing" for the captain. Never jump in after them, as this usually results in two victims instead of one.