Biggest: Allure of the Seas

By the specs, this leviathan of leisure should be in every way the equal of her older sister, Oasis of the Seas. But measurements carried out by NASA engineers show that Allure of the Seas is actually 50 millimeters longer. That’s a little less than 2 inches … of a vehicle that’s 1,187 feet long and with a beam (meaning: width from side to side) of 198 feet. This ship is so large, she has neighborhoods. Seven of them.

Of course, Royal Caribbean International isn’t sitting back on its laurels. For 2016, the line is planning another ship to be a foot longer and 20 feet wider … making space for another 38 staterooms.

Oldest: MV Doulos Phos

There’s a certain pride in having the newest and the shiniest, but a whole other feeling of accomplishment in keeping a maritime tradition alive.

Doulos Phos first sailed as SS Medina for the Mallory Steamship Company in 1914, the year after the first Model Ts were mass produced. Since then, she has sailed for four other companies (including a 20-year jaunt for Costa Cruises and a spell as a charity bookshop), been converted from steam to a fuel-oil engine, and hosted more than 21 million passengers. Not bad for a ship that carries no more than 414 people at a time.

Today, she sails for BizNaz Resources International, a Singapore-based company that plans to eventually convert her to a hotel resort.

Fastest: Queen Mary 2

She’s called the last of the true ocean liners, a distinction that shows in her profile. While most cruise ships look as much like floating hotels as seagoing vessels (and generally amble along at 21 knots — that’s around 24 mph), Cunard Line’s Queen Mary 2 cuts through the waves like a straight razor, zipping between London and New York at a maximum of 30 knots, or 34.5 mph.

She’s powered by two gas turbines and four diesel engines that deliver thrust through four Mermaid pods, two of which can swivel 360 degrees to help manoeuver the ship, as well as three thrusters that can essentially make QM2 spin gracefully in place.

Overall, her power plant can generate 118 megawatts, about twice as much power as a conventional cruise ship.

Longest trip: The World

There are plenty of cruise lines that offer around-the-world sailings, spending a year or more circumnavigating the globe and visiting hundreds of fascinating ports on every continent (yes, including Antarctica). But for passengers, or should we say, residents, aboard The World, the itinerary never has to end.

This is a private residential cruise ship owned by the people who live on board. She travels from port to port, generally spending around three days in each, circling the world every two to three years. In fact, once you’ve bought into one of the 165 residences, you can help shape the ongoing itinerary.

The World has been sailing steadily since 2002. Currently, she’s in Vietnam, but by January, she’ll have gone from Singapore through Thailand to Myanmar and Sri Lanka. By the end of 2015, she’ll have sailed up the African coast and through Europe to Greenland, and then down North and South America to Antarctica — her third visit so far.

In 2016, The World expects to be joined by another luxury live-aboard, Utopia Residences, with 190 units starting at $3.9 million.

Most sailed (literally): Royal Clipper

No, this isn’t the cruise ship that the most people have sailed aboard. Royal Clipper is the cruise ship with the most sails — five masts supporting 42 sheets, making her the largest square-rigged sailing ship in the world.

The flagship of Star Clippers’ three-ship fleet, this 439-foot wind-driven vessel boasts all the romance of the Age of Sail along with the luxurious amenities of the 21^st century. She has three swimming pools and 19,000 square feet of deck space shared by 227 guests. That means there are plenty of little hidden balconies and romantic nooks, as well as a spectacular three-deck dining area and, farther below, a spa and fitness center with underwater portholes. The biggest thrill, though, has to be climbing one of the masts to the passengers’ crows-nest, offering an unrivaled ocean view.

— Grant Balfour