The world's largest cruise ship, Royal Caribbean's Icon of the Seas, set sail from Miami on its maiden voyage Saturday, carrying what amounted to the population of a small city.

The ship, built over 900 days at a shipyard in Turku, Finland, is a monument to enormity, longer than the Eiffel Tower is tall, with 20 decks and room for more than 5,600 passengers (7,600 at maximum capacity) and a crew of 2,350.

To ensure no one goes bored or hungry, the monster ship, registered in the Bahamas, has seven swimming pools including a 40,000-gallon "lake," six water slides, a carousel, what Royal Caribbean says is the largest ice arena at sea, and more than 40 dining venues and bars.

Still bored? There will be 50 musicians and comedians as well as a 16-piece orchestra.

The $2 billion Icon -- the first in Royal Caribbean's new Quantum Class of ships -- is stuffed with the latest technology and, despite its mammoth size, claims to be more eco-friendly than some smaller cruise ships.

The Icon is powered by what its owners say is eco-friendly Liquefied Natural Gas (though some experts say LNG systems can leak damaging amounts of methane gas into the atmosphere).

It also features a system -- microwave-assisted pyrolysis -- for converting waste to energy-producing gas, and a reverse osmosis system to provide nearly all the fresh water the ship needs, the company says.

The Icon was christened in style on Tuesday, when global soccer star Lionel Messi, now with the Inter Miami side, pushed a button to send a bottle of Champagne crashing against the ship's bow.

After leaving its Miami home base Saturday on its sold-out inaugural cruise -- the company says ticket demand was "unprecedented" -- the Icon will spend a week in the Caribbean before returning to Miami.

At 2,000 feet long (365 meters), the Icon will be taking the title of world's largest from a Royal Caribbean stable-mate, the slightly smaller Wonder of the Seas.