How Much Fuel Does A Cruise Ship Hold? (And What It Costs To Refuel)

They're not typically something one thinks about during a luxury cruise, but they're what keeps the metaphorical wheels turning — a cruise ship's fuel tanks. They more closely resemble grain silos than a traditional fuel tank, weighing as much as 307 tons per tank on Royal Caribbean's Icon of the Seas, the world's biggest cruise ship and one of the largest seafaring vessels of all time. These massive units feed the ship's systems with hundreds of tons of fuel per day. So how much would a cruise ship hold?

The answer depends on the ship's size, what kind of fuel is stored, how large the tanks are, and how long the ship's route is. Because all that fuel is heavy, ships only deploy with enough to get to their intended port with fuel in reserve, and typically refuel en route. But in general, a fully loaded cruise ship can hold anywhere from several hundred thousand to over 2 million gallons of fuel.

The cost of all that fuel fluctuates as well, depending on fuel type and what port the ship is using. Fuel prices at this scale are measured by the metric ton, with prices averaging at $664.50 a ton in March 2024. Modern very-low sulfur fuel oil weighs roughly 7.5 pounds per gallon, which equates to 294 gallons per ton, or $2.26 per gallon. That's quite a lot of money when you're talking about a 2-million gallon capacity for some of these vessels. 

Of course, these behemoths only represent a fraction of cruise ships sailing around the world today. Many are substantially smaller, with vessels like the Wind Spirit, operated by Windstar Cruises, displacing just 5,736 tons. This 600-foot ship is even small enough to use sails to boost its efficiency. And while Windstar doesn't publish exact figures, it notes that a ferry about three-quarters as long might sail with up 130,000 gallons of fuel.

For something larger, let's take one of the best-known examples: the Queen Elizabeth 2. In service from 1968 to 2008, it was a full 963 feet long and displaced 65,863 tons, a perfect spot between the two. Its fuel tanks housed 4,381.4 tons of fuel, which it consumed at a rate of about 18 tons per hour. Given that it traveled 5.6 million miles in its lifetime and had a typical fuel economy of 105.6 gallons per mile, that means that it used somewhere in the ballpark of 600 million gallons of fuel over four decades.

Lastly, let's look at a more modern example, the Norwegian Spirit. Norwegian's smallest ship, it displaces around 83,775 tons and holds 354,144 gallons of fuel — a far cry from more massive vessels that may have five or even 10 times the fuel. That's because smaller ships use smaller engines, which in turn require less fuel, already heavy on its own. So as a ship's size goes up, the fuel required to power it scales exponentially.

Modern cruise ships use several types of fuel to power their engines and subsystems, including marine diesel, liquifed natural gas, and heavy fuel oil, also known as "bunker fuel." Take Harmony of the Seas, one of the largest vessels in operation, weighing 226,963 tons. This ship reportedly consumes about 1,377 gallons of fuel every hour at full power, or 66,000 gallons per day. Even less efficient vessels might need anywhere up to 80,000 gallons a day, about 250 tons of fuel. All that fuel powers generators in addition to the ship's main propulsion and electricity subsystems, hence the requirement for such massive fuel tanks.

To get all this fuel, cruise ships use specialized ships in a process called "bunkering." A bunker ship, or bunker barge, operates like a floating gas station, bringing the fuel to the cruise ship and transferring it. In other words, a bunker barge is the high seas equivalent of a KC-46 Pegasus mid-air refueling tanker. 

The rule about fuel prices fluctuating between states and countries applies on the high seas, and some regions offer different grades and prices of fuel than others. Often, the cost of fueling a cruise ship becomes a balancing act between destinations to score the least expensive or best-quality fuel, similar to driving five minutes to another gas station with lower prices. And when you're refueling a 2-million-gallon tank, saving a few extra cents per gallon really adds up.