1. Europa 2
This luxury cruise ship is impeccably designed, with massive chandeliers, outdoor teak decks and an incredible, evocative art collection. It also boasts the highest passenger space ratio at sea. (That means that even if the ship is sailing at capacity -- 516 passengers -- it doesn't feel crowded.) Hapag-Lloyd Cruises, the inventor of the cruise vacation, created the ship with the German passenger in mind, but Europa 2 also draws travelers from the United States, United Kingdom, Belgium and Australia, among other international markets. Passengers enjoy unique itineraries, which include overnight visits to major cities like Barcelona, New York and Sydney. Facilities onboard are smartly designed, with a massive spa complex, magrodome-covered pool deck and a number of gourmet restaurant options.
2. Celestyal Crystal
Greek-based Celestyal Cruises packs a lot into its vessels, but Celestyal Crystal might be the hardest-working cruise ship among its fleet of three. That's because it does double-duty, splitting time in the Mediterranean as well as Cuba. In the Med, it's all about Greece, and passengers visit the big ports like Mykonos and Santorini as well as little gems such as Heraklion and Milos. Celestyal Crystal is also one of the few vessels that does full round-Cuba itineraries. At 1,200 passengers, the ship doesn't have the flashy features of larger, newer ships, but the simplicity and destination focus are appealing. When sailing Cuba, entertainment and activities have a local focus, with Latin-inspired dancing and shows along with Spanish language lessons.
3. P&O Britannia
Brits are plenty familiar with P&O Cruises, but cruisers from other locales might not know the line so well. Britannia is the line's flagship, holding 3,647 passengers. The ship, which sports a 310-foot Union Jack on its hull, features a bevy of activities onboard, including cooking classes at its Cookery Club, lively dancing at its nightclubs, large kids' facilities and multiple pool areas. Passengers can dine at more than 10 restaurants onboard on sailings in the Caribbean, northern Europe and the Mediterranean.
4. SeaDream II
SeaDream unabashedly calls the experience onboard its two ships yacht-like. It's not wrong. SeaDream II, which holds only 110 passengers, brings the idea of intimate and personalized cruising to a whole new level. Passengers onboard the vessel are treated to an all-inclusive experience that has crew at your beck and call. Sure, there's a menu, but if you don't like what's offered, tell them what you want and they'll oblige. Want to bike while ashore? Grab one of the ship's mountain bikes and go for a spin. Itineraries take passengers to the Mediterranean and the Caribbean, and most people who sail like it so much, they come back again and again.
American Cruise Line has been putting ships on the iconic Mississippi River for years. America, which debuted in 2016, offers an intimate experience that is jampacked with shore excursions without being exhausting. The riverboat, which features a showy paddlewheel, can accommodate 185 passengers, and divides its time between the upper and lower reaches of the Mississippi. It features spacious suites, including those for solo travelers. Food is locally sourced, and onboard naturalists and historians provide lectures and more informal information as you cruise.