We didn't book a tour through the ship. Instead we found a booth along the peir where the tenders dropped us off. I had investigated before the cruise and really wanted to try the zip-line tour offered there. (It isn't offered through Carnival) The zip-line tour was great. They gave us instructions and then took us on a bus to the beginning point half way up the mountain. There were 5 lines 2 of which were very long and the view was spectacular. The guides were very personal and made the experience fun and relaxing.
Before and after the zip-line tour we pretty much just wandered around the town shopping. Catelina is a very quaint beautiful sea-shore town that can't help but relax you.