Quantum of the Seas isn't just a floating resort hotel, it's a moveable one. Ignoring all the power needed to run the hotel: to light the rooms and commons areas, cook the food, run the elevators, and spin the slot machines, it takes a lot of power to move the ship.
According to this Wikipedia article, Quantum has two "20.5-megawatt ABB Azipod XO propulsion units." Azipod XO propulsion units are gigantic electric motors (see here). The picture shows a much smaller unit, about 1/10 the size of Quantum's main units.
How much power is 20.5 megawatts? YMMV but here’s what this site has to say. The South uses much more electricity than the North--because of air conditioning--and of course life style is a factor. And so is the extent to which a power source runs at capacity. Bottom line:
Going through the math, a 1,000 megawatt rated coal generator with a 75 percent capacity factor generates about 6.6 billion kWhs in a year, equivalent to the amount of power consumed by about 900,000 homes in the Northeast but only 460,000 homes in the South.
So let’s divide by 1,000 and round: a megawatt looks like between 50 and 100 homes. Each of Quantum’s propulsion units could take care of 20 times that: 1000 to 2000 homes. Double that for two units.
And then there are the bow thrusters, used for maneuvering. Each puts out 3,500 kW, or 3.5 mW and makes them about the size of the Azipod in the picture. That's 14mW more for the four.
Lots of power.