Related Clues:

• Message in a bottle, maybe
• Sign of trouble
• Message from a desert isle, perhaps
• Dashed-off plea?
• Dot, dot, dot, dash, dash, dash, dot, dot, dot
• Smoke signal message, maybe
• Sinker's call
• Ship's call for help
• Distress-call letters
• Distressing letters found 9 times in this puzzle
• Marine Mayday
• Help wanted notice?
• Message that's often repeated
• Alert at sea
• Skipper's distress call