Carnival is the ultimate fun-in-the-sun warm-weather line, and even in Alaska, the Caribbean-focused operator retains its "Fun Ship" philosophy. Sure, you'll be cruising past glaciers and on the lookout for whales, but you'll be doing it with people who like to take in the natural wonders with a multicolored party drink in hand. Drinking and R-rated comedians are part of the scene, as are "hairy-chest contests" and the like.

Entertainment is among the industry's best, with each ship boasting a dozen dancers, a 10-piece orchestra, comedians, jugglers, and numerous live bands, as well as a big casino. Activity is nonstop. Cocktails begin to flow early, and through the course of the day you can learn country line dancing or ballroom dancing; take cooking lessons; learn to play bridge; watch first-run movies; practice your golf swing by smashing balls into a net; or just eat, drink, shop, and then eat again. Alaska-specific naturalist lectures are delivered daily. In port, Carnival offers more than 120 shore excursions, divided into categories of easy, moderate, and adventure. For kids, the line offers Camp Carnival, an expertly run children's program with activities that include Native arts and crafts sessions, lectures conducted by wildlife experts, and special shore excursions for teens.

Carnival's ship in Alaska cruises the Inside Passage route with round-trip departures out of Seattle.

Passenger Profile -- Overall, Carnival has some of the youngest demographics in the industry. But it's far more than age that defines the line's customers. Carnival executives are fond of using the word spirited to describe the typical Carnival passenger, and indeed the descriptor is right on target. The line's many fans increasingly come from a wide range of not just ages, but occupations, backgrounds, and income levels, but what they share is an unpretentious, fun-loving, and outgoing demeanor. On Carnival, you'll find couples, a few singles, and a good share of families, but the bottom line is, this is not your average sedentary, bird-watching crowd. Passengers want to see whales and icebergs, but they also want to dance the Macarena.

Ships -- The 2,124-passenger megaship Carnival Spirit returns to Alaska in 2012. It offers plenty of activities, great pool and hot-tub spaces (some covered for use in chillier weather), a big ocean-view gym and spa, and more dining options than your doctor would say are advisable. Sample nightly rates per person: Lowest-price inside cabin $125, lowest outside cabin $161, lowest suite $261 for a 7-night Inside Passage cruise.