How long can a cruise ship stay at sea?

With a cruise ship’s vast size and generous onboard facilities (here's looking at you, Icon of the Seas) it’s logical to imagine that most cruise ships could remain at sea for weeks, if not months, at a time.

Quite frankly, for some passengers, it's tempting to hope that the ship encounters an event destined to keep you upon the waves far beyond your original booking. After all, cruise life can be utterly luxurious and an escape from life's pesky problems. However, there are limits as to how long the likes of Sky Princess or Cunard's Queen Mary 2 can safely stay at sea.

It's not as ridiculous a concept as it sounds. There's a range of events and possibilities that could prevent your cruise ship from docking. Zombie outbreaks and Hollywood-style natural disasters aside, very real events – wars, hurricanes, viruses and mechanical breakdowns – can leave a cruise ship unable to dock. And should that happen, how long can a cruise ship stay at sea when disaster strikes?

Well, that’s a slightly tricky question as there are many different factors at play. Your ship’s ability to reside at sea is largely determined by the vessel itself, as well as the supplies (sweet Jesus, we're out of coffee!) it carries onboard while external factors always add an element of unpredictability, even to the best-laid plans.

Seagoing endurance: Your cruise ship’s capacity at sea

A cruise ship’s ability to stay at sea is dictated by two main factors – the fuel and catering supplies onboard.

Much like a car, your cruise ship can only carry a given amount of fuel within its onboard tanks. The fuel tanks on cruise ships are considerable and for good reason – your ship can burn through as much as one thousand gallons of fuel per hour when underway. Roughly an inch per gallon burned.

Larger ships naturally boast larger fuel tanks, but that doesn’t mean the largest ships can stay at sea for longer. With increased ship size also comes increased weight and hydrodynamic drag so, when it comes to fuel economy and the ability to stay at sea for longer, a bigger cruise ship isn’t always best.

In turn, how long the fuel will last is usually determined by the demands that your cruise ship has to handle. If a ship has to make way faster – perhaps because of the late return of pier runners at a previous port or another unexpected delay – then fuel will run out faster.

Equally, if there is a significant number of passengers onboard – all using cabin heating controls and onboard chargers – this will also drain fuel more rapidly.

It is important for a ship not to run out of fuel. Not only would there be the inconvenience of lights going out and onboard amenities becoming mostly redundant, but a powerless ship is vulnerable to being carried adrift. Dark fates have awaited ships with that problem.

Be assured however that cruise ships carry both the fuel that they need to safely complete their planned itinerary as well as additional fuel to add contingency should plans change.

Even just wind direction can influence a cruise ship’s fuel consumption. It therefore always makes sense to allow for more fuel than would otherwise be needed.

Some cruise ships can make use of at-sea refuelling opportunities. Some can top-up from fuel barges or a tanker. However, most ships do not do this. Instead, they refuel at nominated ports while carrying enough to tide them over in between.

Meanwhile, just as important as the ship’s fuel consumption, is the amount of food and water required for those onboard.

With this in mind, most cruise ships carry enough food, water and other supplies to sustain their passenger compliment for a week or two at sea. They may also replenish stock while temporarily docked in port. Perishable items are stored in refrigerators or frozen areas while dry or canned goods are packed in generous quantities.

In addition to bottled water, many cruise ships have advanced desalination systems. These convert seawater into drinkable water so, even if a ship’s progress is delayed, there will always be a constant water supply.

How cruise ships handle extended stays at sea

There are many reasons why a cruise ship carries more fuel and catering supplies beyond what will be required for its official itinerary. There is always the possibility of the unexpected occurring, including some of the scenarios below.

Storms and bad weather

If there’s one factor that can scupper carefully formulated plans, even upon land, it’s the weather.

Many oceans are renowned for presenting ships with turbulent seas during storm season. The North Atlantic, which presents a tricky sail at the best of times, is particularly punchy between September and February. Simultaneously, the Bay of Biscay – situated between western France and northern Spain – also tests sailors with frequent storms.

Meanwhile, cruisers heading to – or from – America often have to contend with hurricane season, as do those travelling within the Caribbean. Further south, down by Cape Horn, cruise ships contend with ‘Drake shake’ as they cross between South America and the Antarctic.

With so many weather-related hazards out at sea, cruise ships come prepared. Most ship bridges now contain satellite imaging systems, weather maps and software that can model incoming storm fronts. It is also common for a ship to converse with a land-based meteorologist or command centre who monitors conditions.

If incoming weather looks to be particularly rough while a cruise ship is out at sea, a captain may opt to travel faster or divert course to avoid the front altogether. If this is not possible, a cruise ship may instead press on while utilising onboard stabilising technology.

If conditions are particularly testing, a ship may take shelter in the lee of an island. On other occasions, a cruise ship is perfectly safe and comfortable at sea but must stay away from shore due to a storm or hurricane that has made landfall.

While many of these options result in itinerary changes, passenger safety must always remain top priority. The contingency of having extra fuel and supplies onboard means the worst of any weather system can usually be avoided.

Outbreaks: When viruses prevent docking

Until the outbreak of Covid-19 in 2020, the thought of being stuck onboard a cruise ship because a virus had broken out would likely have sounded a tad ridiculous. However, that has all changed given that most modern-day cruise passengers have lived through the Covid pandemic.

In early 2020, Westerdam of the Holland America line was unexpectedly stuck at sea for thirteen days due to fears that the Covid virus may have broken out and spread onboard. Originally bound for Japan, the cruise ship found itself caught in the beginning of the pandemic and unable to successfully negotiate a port at which to dock.

Having been turned away from Thailand, Japan, Taiwan, Guam and the Philippines, MS Westerdam and her 2,257 passengers were finally welcomed at Sihanoukville Seaport in Cambodia on February 13, 2020.

As Westerdam arrived, there were no confirmed cases of Covid onboard and Cambodia was praised by the World Health Organisation for receiving the ship.

Rerouting to avoiding conflict

Although a less common reason for having to remain at sea, sometimes cruise ships have to suddenly reroute due to geopolitical tensions and conflict.

In October 2023, many cruise lines began cancelling their plans to dock within Israel after a surprise attack on the country by the Palestinian militant group; Hamas.

Similarly, many cruise lines have withdrawn tours to St. Petersburg in Russia due to the ongoing war in Ukraine. St Petersburg previously featured in many Scandinavian itineraries but many lines including Royal Caribbean; Viking Cruises; Norwegian Cruise Line and Atlas Ocean Voyages have all adjusted their tours.

Many now call into the alternative venues of Finland and Estonia within the Baltic region in place of former Russian and Ukrainian ports.

Mechanical breakdown

In the event of mechanical woes, both captain and crew will quickly establish both the cause and remedy for the issue. If an engine fails, a cruise ship may not actually need to stop, for there are usually several engines onboard.

Where there is a more serious hinderance, the captain may accept a tow from another ship or disembark passengers onto an alternative vessel.

In most incidences of mechanical breakdown, passengers will be asked to stay onboard as the cruise ship is commonly regarded as the safest place to be and the safest way to return to port.

How long a cruise ship can stay at sea? A complex answer

Unless other factors intervene, a typical cruise ship is capable of remaining at sea for an average of 12 days.

To allow wiggle room for the unexpected, you’ll normally find a cruise – if not docking anywhere on route – will conclude after 7-10 days while still having fuel and supplies to spare.

Given that cruise ships are often hundreds of miles away from the nearest shore, it makes sense to allow for a longer stay at sea than what would originally be planned for. The extra fuel and supplies will keep everyone comfortable should the unexpected arise.