I would urge you to consider Captain Marvin's in Grand Cayman. Since you tender into the port (all ships tender to avoid damage to the coral reef), it is easy to get to Captain Marvin's. Step off the tender, walk out to the street, turn LEFT, go down two blocks, on the RIGHT is a small group of storefronts. Captain Marvin's is there. Go in, sign in, a van will then take you to the other side of the island where you will board, newer, clean, well run boats! There are several crew members so you will be very well cared for, as well as assisted once you arrive! They guys are super!!!!!
They will return you to the office at the end of the excursion...you are downtown so you can browse, shop or head back to the ship!
Google Captain Marvin's and review their web site....