There was also that Daily Mail boat -the offshore station that never was.

And some long defunct website claiming that there was an AM broadcast transmitter on the Titanic (this when AM landbased technology was not so much in its infancy as embryonic)

IIRC the German offshore station operated in French waters with the tacit blessing of the French government so not a pirate in the true sense of the word. (Then again the Voice of Peace off Israel operated in some legally interesting grey zones).