What is the correct distress signal in Morse code?

In Morse code (CW), the internationally recognized distress signal is 'SOS', transmitted as a continuous string of three dots, three dashes, and three dots (...---...). It was adopted because its distinct, continuous rhythm is easy to send and highly recognizable even under poor signal conditions. 'MAYDAY' is the equivalent distress signal used for voice transmissions, so it is incorrect for Morse code. 'CQD' is a historical distress signal used in the very early days of wireless telegraphy but was eventually replaced entirely by SOS.