The ongoing search and rescue effort for the missing Titan submersible with five people on board, involving a huge response from American, Canadian and French authorities, is vast in scale, including both the U.S. Navy and the Coast Guard.

The expense for such an endeavor is likely to be equally great, and it is unclear whether taxpayers in the countries involved, ultimately, will be required to pay it. The passengers aboard the submersible paid $250,000 each for the experience of diving to the Titanic.

“These people paid a lot of money to do something extraordinarily risky and hard to recover from,” said Chris Boyer, the executive director of the National Association for Search and Rescue, a nonprofit that focuses on wilderness rescues. The rescue mission, he said, would “probably cost millions.”

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In the United States, search and rescue efforts — who conducts them and who pays for them — depend on where you get lost, Boyer said. Some states, such as New Hampshire, charge individuals for rescues if the people are determined to have been reckless.

Cynthia Hernandez, a spokesperson for the National Park Service, said in a statement that the agency does not charge for search and rescue operations that occur within its parks because it considers them a public service. The park service conducted 3,428 search and rescues last year.

But, she said, when the cost of search and rescue efforts “crosses a certain threshold, funds may be diverted from NPS funds for other types of programs or projects.”

It is unknown whether OceanGate Expeditions, the company that provided the excursion to the Titanic ruins, required its participants to sign up for any trip insurance.

The organizers of risky and adventurous expeditions, including operators like Abercrombie & Kent and Black Tomato, said that they require extensive insurance policies. Peter Anderson, managing director of the luxury concierge service Knightsbridge Circle, said the company works with services like Covac Global that can “evacuate and repatriate our members for medical emergencies.” But even the minimum policy, $100,000, would not come close to paying for the current efforts.

The Coast Guard did not immediately respond to questions about the expense of past extensive search and rescue efforts.

In 2021, it rescued Cyril Derreumaux, an experienced kayaker who was about a week into an attempt to paddle 2,400 nautical miles from the California Coast to Hawaii. The Coast Guard estimated his rescue, which involved a helicopter and at least one diver, cost $42,000, according to the San Francisco Chronicle.

Derreumaux, who lives in Marin County, California, and is now 46, emphasized in an interview that his goal was to fulfill a dream and that he was not a tourist who had undertaken the venture with minimal training. He received backlash after being rescued, he said, with some people saying that the effort was costly and unnecessary. A stranger even sent him a Venmo request for tens of thousands of dollars, Derreumaux said.

Derreumaux said he was thankful to the Coast Guard for saving his life, along with the lives of many others in need of its help.

“I would not have called the Coast Guard if it weren’t a life-threatening situation,” he said.

He attempted the trip again the following year. This time, he was successful.

“I knew I had what it takes to do it,” he said. “I think it’s part of the human spirit of trying to do things that are really hard for what it teach us about human resilience, determination and to do things that maybe don’t make sense.”

Of the Titan’s passengers, Derreumaux said: “Their lives are worth saving.”

This article originally appeared in The New York Times.