Fished Dunstanborough Castle just the once, but WILL RETURN! My memory is, as well as being the most marvellous place to fish (could well be North Wales!!) that it was potentially dangerous in high sea (as well as being incredibly rough bottom) Has your mate got Household Insurance? If I lose anything of value that's my first port of call!
Had my Stag Night (day?) over forty years ago fishing on a boat in a lake in East Anglia. I dropped a reel overboard and was off after it before my best-man and a mate pulled me back. They rekoned that you can't swim if you are really plastered!