A cruise ship might have several restaurants, a theatre and a spa, but there's another facility you probably hope never to visit: the medical centre.
Modern ships have doctors and nurses who can treat everything from minor injuries to serious illnesses. The less reassuring news is that their services aren't included in your fare, and a medical emergency at sea can become extraordinarily expensive.
In the worst cases, the bill can run into tens or even hundreds of thousands of pounds. So what are passengers actually charged for, and who pays if something goes wrong?
Unlike an appointment with your GP, visiting a cruise ship's doctor generally means receiving a bill.
Medical centres operate as private facilities, charging separately for consultations, medications, diagnostic tests and treatment. Some also apply additional fees for out-of-hours appointments.
The exact price varies considerably between cruise lines, ships and the care required.
In one firsthand account published by The Points Guy, a passenger aboard a Carnival ship paid $214.80 for a medical appointment, including $170 for professional services and $44.80 for antibiotics. More serious treatment can cost considerably more.
In 2022, American passenger Vincent Wasney suffered three epileptic seizures aboard Royal Caribbean's Independence of the Seas. His onboard medical care, which included medication, blood tests and observation, resulted in a bill of $2,500.22.
According to an investigation by KFF Health News, he received the bill while awaiting evacuation from the ship.
These are individual cases, rather than standard tariffs. But they illustrate how quickly medical costs can accumulate, particularly when treatment involves more than a brief consultation.
And unfortunately, there's no NHS discount for being British.
The largest bills usually arise when a passenger needs treatment beyond the capabilities of the ship's medical centre.
While cruise ships can provide emergency care and stabilise seriously ill patients, they aren't equipped to perform complex surgery or deliver the full range of treatment available in a hospital.
Depending on the circumstances, the captain may divert to a nearby port, arrange a transfer by boat or coordinate a helicopter evacuation.
Fred. Olsen Cruise Lines warns that a helicopter evacuation at sea can cost between £20,000 and £65,000, although actual charges and who bears them depend on the rescue arrangements. And reaching hospital may only be the beginning.
A patient could require surgery, several days of treatment abroad and specialist transport home. The Foreign, Commonwealth & Development Office (FCDO) gives the following examples of potential overseas medical costs without insurance:
Source: FCDO foreign travel insurance guidance. These are general overseas medical scenarios, not cruise-specific bills.
Costs depend on the location, treatment and transport required. Not every emergency involves an expensive evacuation, and some coastguard rescues are provided without charging the patient.
Nevertheless, it's easy to see how a medical emergency could become considerably more expensive than the cruise itself.
Usually, the passenger is responsible for the initial onboard bill.
P&O Cruises, Princess Cruises and Norwegian Cruise Line all confirm that medical charges are added to passengers' onboard accounts, with itemised receipts provided for insurance claims.
Even if you have comprehensive travel insurance, the ship's medical centre may not bill your insurer directly.
For smaller expenses, you may need to pay first and claim reimbursement afterwards, subject to your policy's terms and excess. For major emergencies ashore, an insurer's medical assistance team may be able to arrange payment directly with the hospital.
It's worth requesting copies of your medical records and itemised invoices before leaving the ship.
After all, discovering that you need paperwork from a doctor somewhere in the Caribbean is an unwelcome addition to an already difficult situation.
This is an especially important distinction for British passengers.
A UK Global Health Insurance Card (GHIC), or valid UK European Health Insurance Card (EHIC), can provide access to medically necessary state healthcare in eligible European countries.
But it doesn't cover treatment aboard a cruise ship, even when the vessel is docked.
The NHS Business Services Authority confirms that passengers may qualify for eligible state healthcare once transferred to a hospital ashore, but onboard treatment remains outside the scheme. Neither card covers private medical treatment or repatriation to the UK.
So even on a Mediterranean cruise, where you might reasonably expect European healthcare arrangements to offer some protection, suitable travel insurance remains essential.
The most important protections are emergency medical treatment, evacuation and repatriation.
Some cruise lines make these mandatory. P&O Cruises and Cunard, for example, require passengers to have at least £2 million in medical and repatriation cover, including emergency evacuation.
Before travelling, check that your policy explicitly covers cruises, every destination on your itinerary and the full length of your holiday.
Any pre-existing medical conditions must be disclosed and accepted by the insurer. It's also worth checking the policy excess, the emergency medical assistance arrangements and whether companion travel or accommodation costs are included if you're hospitalised abroad.
One easily missed distinction is that medical cover for a cruise isn't always the same as optional cruise disruption cover. Benefits for missed ports, cabin confinement or unused excursions may require an additional upgrade.
The FCDO recommends checking with your insurer before travelling rather than assuming an ordinary holiday policy will meet a cruise operator's requirements.
If you're unwell, seek help from the ship's medical team promptly. Don't delay necessary treatment because you're worried about the cost.
As soon as it's practical, contact your insurer's 24-hour emergency assistance service, particularly if hospital treatment or evacuation may be required.
The Financial Ombudsman Service explains that insurers often need to assess proposed treatment, authorise expenses and decide on medically appropriate arrangements for getting a patient home.
Keep your policy details accessible, ideally somewhere your travelling companion can find them too. And retain medical reports, prescriptions and receipts in case you need to make a claim.
Thankfully, most cruise passengers never face a serious medical emergency. But if the unexpected happens, appropriate insurance can make an enormous financial difference.
A few minutes spent checking your policy before departure is a considerably better prospect than discovering the price of an air ambulance somewhere in the middle of the Atlantic.