Colon 2000, Panama
Great for: Dining, drinking, nightlife
If you've only got six hours: Take the hour-long trip into Panama City. It's a steel-and-glass marvel, and the most modern city in Latin America.
Yes, the Panama Canal and Miraflores locks are the obvious draw here, and a cruise stop is the easiest and least congested way to see them both. But at the relatively new Colon 2000 port, you'll be docking so close to the canal, seeing them won't take up much of your time. There's not a ton of shopping to be done here, unless you're looking to import electronics from the world's biggest duty-free zone, so take a ride to Panama City, just over an hour away. It's the only foreign metropolis you can visit on a Caribbean cruise, and gives you a chance to see how this country has exploded economically since regaining control of the canal.