Radio Caroline was the first and longest-running of the offshore 'pirate' radio stations that operated off the British coast just outside of territorial waters in an effort to circumvent the restrictions on radio at the time.

This video is from the 1980s incarnation of Radio Caroline, their ship Ross Revenge is still around and Caroline operates it as a licensed station (set to be among the last of the British AM stations) although she's in urgent need of dry-docking and repairs. There's a lot of HN worthy aspects of the story, not least in the technical challenges of operating multiple medium wave transmissions in the harsh marine environment.