There are a bunch of travel activities that can be done on both land and at sea. We can play golf on land but sail to some of the world's best courses by sea. We can dine at a fine restaurant on land and find similar experiences at sea.

But some things are available only on a cruise.

If those are good or bad things kind of depends on how you look at them.

1. Unpack once, see several places. Unlike any other type of travel, once you make it to your cruise ship, you are home free. Your floating hotel will take you to multiple destinations with no flights, cabs, cars, trains or buses to catch to get there.
2. Be a complete idiot. This is where you want to wear that bathing suit that doesn't quite fit right, sing karaoke for the first time or try out your new pickup lines. Odds are you will never see any of the people you are sailing with ever again.
3. Eat, non-stop, 24 hours a day on pretty much any cruise ship. Unlike real life, it is odd for there to NOT be food readily available all the time. What makes this unique to cruises is that you paid for it up front, so there is no charge as you belly-up to the buffet.
4. Fall into the ocean. It is not easy to do but you could if you tried. This is also not something you should want to do. If the fall did not kill you, the eventual drowning that comes along with it will. While the height of your cruise ship may be similar to that cliff you saw someone jump off of on TV, what lies below is totally different.
5. Learn something new- On-board enrichment programs cover everything from acting to dance lessons. In the ship's fitness center, qualified trainers are standing by to help you get ready for your next mountain climbing expedition.
6. Get Seasick but you almost have to want to be sick for that to happen. There are so many different ways to avoid motion discomfort that there are few reasons to experience it.
7. Survive a pirate attack- If you are in the Indian Ocean, anywhere close to Somalia, you could be attacked by pirates. Major cruise lines don't sail there anyway, especially since Seabourn Spirit had to outrun them.
8. Save a lot of money- Dollar for dollar, cruise vacations stack up very nicely compared with land vacations. Compared with backpacking? Not so much. But compare a week at sea to a week in Vegas and you'll get the idea.
9. Get married at sea. It is different than getting married on land. First off, you won't be driving off to your honeymoon with a "Just Married" sign on your car. Unlike a Vegas wedding, you'll have a hard time finding Elvis to perform the ceremony too.
10. Experience a day at sea This is probably one of the very best parts of a cruise vacation and surely one that separates cruises from all other travel options. Being completely surrounded by ocean, in all directions and as far as you can see, is a humbling experience everyone should have at least once. Odds are you will never see anything as big as the ocean that stretches to the end of the Earth.