I did capitan marvin a little over a year ago! They were awesome. They timed the trip so there were fewer boats at stingray city when we arrived (2 instead of the 5 we saw the first time we motored by) They provided an underwater scuba cameraman,
also....marvin goes to the sandbar (much better than city). I WILL take marvin next time i am in grand cayman.
That's how I booked my trip.