lowden1, if you'll look down the main page just a little, you'll see Alaska Port Chat. There are tons of posts there about all different kinds of excursions. You might find something that really interests you.
I hope your son will go with an open mind. There is so much to do on board ships. Since y'all are going to Alaska, the pool time might not be as great as the Caribbean. However, just watching the ocean for a possible whale or some ice flows and the shore line is magnificent. They have all kinds of different activities, trivia games, wine tasting, bingo, shops, casino, board games, library, and much, much more.
Hope this helps some!