towels are for either sitting on or if at front of boat place them on the rope floor as the ropes are hard on your feet when dancing or Playing games. Use resort towels but dont forget them.
definitely cash for the crew .... they are awesome! My wife didn't wear a top when we boarded the boat as she didn't want to loose it .... same with a second cover ... as you can see from our album she just put on the wrap they sell on the boat when we got to the island. Actually I don't think they make the island stop anymore so no need to ever cover the puppies! When you stop for lunch you don't have to wear a top. Plenty of sun screen We also brought 2 of the large bottles of water to try to stay a little hydrated. of course AWIC!!!! Waterproof camera..... otherwise you will have a hard time remembering what you did ... just be respectful when snapping the pix! Have a great time!
In addition to all the above, definitely take a sense of humour. Definitely leave behind your inhibitions.