These are the cruise lines you know even if you've never set foot on one. They're the ones with the catchy TV spots, glossy magazine spreads, and omnipresent website banner ads that make cruises seem like sheer paradise - and for many people, they really are.
Today's mainstream ships are part theme park, part shopping mall, part gym, and part faux downtown entertainment and dining district, all packaged in a sleek hull with an oceanview resort perched on top. The biggest are really big: 14 stories tall, 1, 000 feet long, with cabin space for between 2, 000 and 5, 000-plus passengers and a couple of thousand crewmembers. Most of the mainstream lines have spent the past 10 years pumping billions into ever-newer, bigger, and fancier ships, and the intense competition means they're constantly trying to outdo each other with entertainment and activities. The newer the ship, the more whoopee you can expect: open-air boardwalk districts, bowling alleys, water parks, ice-skating rinks, outdoor movie theaters, surfing machines, giant spas, rock-climbing walls, full-size basketball courts, and virtual-reality golf, plus classics like hot tubs, theaters, water slides, and bars, bars, bars. The action is just outside your cabin door, though if you crave some downtime, there's always your private balcony or some quiet lounge that's deserted while everybody else is living it up.
Overall the atmosphere is very social and active, especially on warm-weather cruises in the Caribbean, The Bahamas, Bermuda, and Mexico, which tend to draw the youngest mix of fun-loving, like-to-party passengers (lots of 20s, 30s, and 40s). Itineraries in Alaska and New England tend to draw a mellower crowd, mostly in their 50s and up.
The more elegant and refined of the lines are commonly referred to as premium, a notch up in the sophistication department from others that are described as mass-market. Quality-wise, they're all more similar than they are different, especially in regard to dining and entertainment. Ditto for lines such as Azamara and Oceania (and half the Holland America fleet), whose midsize ships are almost a throwback to the days before supersizing. Though these lines' vessels are tiny compared with the Royal Caribbeans, Carnivals, and Princesses of the world, they're in this group because they offer well-rounded cruises for a diverse mix of passengers.
Dress Codes - Aboard most lines in this guide, most nights are designated as casual, "dressy casual, " or semiformal, with one or two being formal or "formal optional." But, these days, those are more suggestions than rules, and in any case, most ships these days have at least one casual dining venue open every night in case you just can't face dressing up at all.
Note: Cruise lines have been graded on a curve that compares them only with the other mainstream lines.