We did the catamaran thing. It was **most** fun.
The surf was rough (I guess relatively speaking) so the first beach we were supposed to go to wasn't calm enough. We went to another one further away which was calmer. The water wasn't very clear from all the mixing so you couldn't see much--if anything. It was still fun!
They stopped about maybe 50ft or so from shore and then you swim to shore. They have mask, fins, vest, etc. The sand was very very soft but also very weird....strange texture. Plus when we were done I think I had more sand in my shorts than was left on the beach. I thought I'd never get that sand out of everything...including me!
On the way out they had fruit punch and when we left the beach we had sandwiches and your choice of rum punch, beer, regular punch. While sailing back we had champagne.
All in all it was very enjoyable and I would do it again. It was so nice to be out on the water and so close to it. We were a group of 3 adults, but all the kids on board seemed to have fun too. Do note about the swim to shore...I think my sister about had a heart attack thinking she'd never be able to swim that far. She was fine! I've never jumped off a ship into water where I can see the bottom in my life...and I survived to tell about it.