Cruising is one of the best vacation values for your money, with so many aspects of your travel covered in the cost of your cruise fare. But competition for passengers is tough, and cruise companies need to be constantly innovating, both in terms of itineraries and shore excursions, and with new ships and an adventurous array of on-board activities.

Use to be that a basketball court or a putting green was exciting. That's nothing. On cruise ships, now you can skydive, ride a zipline, walk the plank, order from your favorite robot bartender, drive a race car, and swing on a trapeze.

Besides the swimming pools, surfing simulators, mini golf, musical theater, art auctions and duty-free shopping that are staples of most cruises, here are some fun things you can do on cruise ships, without ever leaving the boat.