Are you specifically looking only for c/o? If so, I think you are limited to Tiko Tiko (still around, for sure, check out their website for their various cruises), Paul's nude cruises (which are on a SPEED boat, not a cat, not bad, just a different experience) and I believe that occasionally Neil from Celine runs some c/o cruises. Otherwise, if you are looking specifically for c/o, it would have to be a private cruise.