SOS is three short signals, three long signals, and three short signals: ...---....
Send it as one continuous signal
Although it is often printed as the letters S O S for learning, the distress signal is normally sent as a prosign without ordinary letter gaps. Keep the one-unit gaps between the individual dots and dashes, but do not insert a three-unit pause after each group of three.
Using a light
Cover and uncover a steady light, or switch it on and off. A short flash is one unit; a long flash is three. Keep one unit of darkness between every flash. After the complete SOS pattern, leave a clear pause before repeating it.
Using sound
A whistle, horn, buzzer, or repeated tone can carry the same rhythm. Make each long sound about three times the length of a short one. Consistency matters more than playing quickly.
Repeat and make yourself visible
Repeat the complete pattern, pausing between repetitions. Combine the signal with other ways of attracting attention when possible. In a real emergency, use the fastest available method to contact emergency services and give your location.
A signal, not a spoken abbreviation
SOS was chosen for its distinctive pattern, not as an abbreviation for “save our souls.” It is internationally recognized as a distress signal, but modern maritime distress communication also uses radio procedures, digital selective calling, emergency beacons, and other systems. The U.S. Coast Guard lists SOS among international distress signals rather than as the only method.