So, everyone knows what a cruise is, but when you are asked about Land, what is it? 

When you take a cruise, it's part Land and part cruise.  The travel to a cruise port would be just like a Land tour.  Being on the ship and making stops to do excursions, is stopping to do a Land tour.  If you cruise out of, say Miami, and go out in the Caribbean spending a week relaxing, sun, beach, sometimes up a mountain.  A cruise gives you a place to eat, sleep, and have a good time.  A land tour can be the same thing, Sandals, Beaches and 100's of other resorts give you a place to eat, sleep and have a good time.  If you don't like cruising during hurricane season, maybe consider something different.  

If you are traveling to Europe, Australia, Asia, South America, Africa, or Alaska, for a cruise, it took you a long time to get there.  It's probably a bucket trip, or something special.  Would you consider a few extra days doing a Land tour?  Visit a winery in Italy, or France.  Throw in a European high-speed train and travel Europe for a few days, visit Paris, London, so many places are possible.   It can be what you make of it, luxury travel, or modest bed and breakfast, to someplace you've always wanted to visit while you're somewhere.  

Almost everyone doing a cruise in the US, flies in, maybe a day early, enjoys the days on the ocean, when the ship returns, it's off to the airport.  Much of that is you have a one-week vacation, or the kids are out of school for the week.  With a little planning, when you returned a car or bus could be waiting to take you to a few days of relaxing, visiting museums, a hotel to see what's in the big city the ships return to.  

There are so many possibilities for land tours, go to Alaska, get off in Anchorage, take the train to Danali, a night or two in a national park hotel, or go to Fairbanks and spend a couple days exploring.  You could try Australia, it's a long flight, but if you plan it right, most of it could be nighttime and you could sleep through a lot of it. If it's Australia, you've already planned for more than 10 days, a few more may stretch your budget, but Australia, is like Europe, Asia, South America, Africa, or Alaska, it's not like that cruise every year, it's a long-planned vacation.