So much! You can watch the shows they have every night, sing/watch karaoke, or my personal favorite is to go clubbing at night. You could always chill by the pool, play some sports like golf, bball, dodgeball, volleyball, etc. they have so many activities going on that you can learn how to salsa dance to napkin fold to decorating cupcakes lol its so much fun :)
Lots! They have all kinds of games they play with the passengers. (I won the brain teasers game!) All kinds of shows. Depending on your age, there are casinos and clubs. Plus when you are docked there are all kinds of excursions. On one cruise I saw some great Mayan ruins on a beach. Toured the ruins and then went swimming on the most beautiful beach!