All five people aboard a missing submersible known as Titan are believed to be dead, the company that operated the submersible said on Thursday. The crew went missing June 18 shortly after venturing into the deep sea to tour the Titanic wreckage site.

“We now believe that our CEO Stockton Rush, Shahzada Dawood and his son Suleman Dawood, Hamish Harding, and Paul-Henri Nargeolet, have sadly been lost,” OceanGate Expeditions confirmed in a statement. Authorities reportedly found debris that indicated the vessel may have imploded.

Read More: With a Titanic Tourist Vessel Missing, Here’s What to Know About Submersibles

The ​​sub was carrying a pilot, three wealthy adventurers, and the company’s CEO to see the remains of the Titanic, 2 miles beneath the water’s surface, when it lost contact.

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“I am thinking of Suleman, who is 19, in there, just perhaps gasping for breath … It’s been crippling, to be honest,” said Azmeh Dawood, the sister of Shahzada Dawood and aunt of Suleman Dawood. “I personally have found it kind of difficult to breathe thinking of them.”

The family of British explorer Hamish Harding wrote in a statement that, while they would mourn his loss deeply, they felt some consolation knowing that he died doing what he loved.

“He was one of a kind and we adored him. He was a passionate explorer — whatever the terrain — who lived his life for his family, his business and for the next adventure,” the family said in the statement. “What he achieved in his lifetime was truly remarkable and if we can take any small consolation from this tragedy, it’s that we lost him doing what he loved.”

The crew’s disappearance—and the voyage’s $250,000 per person price tag—has brought a spotlight to the growing and largely unregulated deep-sea tourism industry that is almost exclusively patronized by the ultrawealthy.

Rise of Deep-Sea Tourism

In recent years, underwater tourism has expanded beyond the average snorkeling or scuba-diving trip.

OceanGate, which began taking tourists on its Titanic tours in 2021, joins a growing number of underwater tourism experiences that expose travelers to the depths of the ocean—often for a steep price. In “Lovers Deep”, a luxury submarine hotel launched in 2014, couples can circle the reefs of St. Lucia starting at around $300,000 a night. For those wanting less sticker shock, DeepflightAdventures and Four Seasons began offering in 2018 an hour-long tour along the Maldives in a super Falcon 3S submarine for $1,500.

“Extreme adventures used to be the domain of the lunatic fringe,” says Jon Heshka, an associate professor at Thompson Rivers University in British Columbia whose research focuses on adventure studies “Now, in order to gain access to these remote areas of the world where governments impose permit fees and requirements … you really have to pay for it.”

OceanGate also offers other pricey experiences for “citizen explorers” looking to traverse the depths of the seas (via the same Titan vehicle that’s gone missing), including a three-day, two-night expedition to hydrothermal vents off the coast of Portugal that costs $250,000 and a Bahamas dive with tickets starting at $45,000.

Big Risks and Little Regulation

Deep-sea excursions, much like the buzzy “space-tourism” industry that has gained popularity in recent years, have few regulations in place. Extreme tourism, Heshka says, rarely finds itself facing government interference.

“The government won’t regulate until there’s a demonstrated need that industry has failed to self regulate. If things are humming along and the activities are being administered, more or less incident free, and businesses are making money and clients are willing to shell out the coin, there’s no need for the government to become involved,” says Heshka. “However, if there are particularly high profile incidents, then that becomes the business of the government to regulate.”

Read More: ‘Debris Field’ Found Near Titanic in the Search for Missing Titan Vessel

Some of the Titan’s former passengers have spoken out about the safety conditions on the submersible. A camera operator for Discovery Channel’s “Expedition Unknown,” Brian Weed did a test dive on the Titan in May 2021 and told NBC, “The moment we started the test dive, things started going wrong.” Mike Reiss, a writer and producer who has worked on “The Simpsons,” said that on all four dives he did with OceanGate, the crew lost communication with the host ship, according to ABC News. One passenger who was supposed to be on Sunday’s dive told Good Morning America he pulled out at the last minute because he feared for his safety.

In a 2019 blog post explaining why the company did not meet classification standards usually required of ocean vessels, OceanGate said that the company’s “new and innovative designs” could not yet be judged by existing regulatory standards. “By definition, innovation is outside of an already accepted system,” the company said. “However, this does not mean that OceanGate doesn’t meet standards where they apply, but it does mean that innovation often falls outside of the existing industry paradigm.”

The Titan’s passengers are required to sign a waiver that lists “physical injury, disability, emotional trauma or death” as the potential risks, according to CBS reporter David Pogue, who boarded the sub last year. Mike Reiss, one of the submersible’s previous passengers, told the BBC that the waiver mentions death “three different times on page one.”

But Heshka says that such liability waivers are “ubiquitous” when it comes to extreme sports and activities, even for things as common as skiing.

“Canadian and American ski hills to varying degrees, administer waivers that will include in the list of hazards that could be encountered all the things that can go wrong on the mountain, like critical injury, paralysis and death.”

Most people tend to take the risks with a grain of salt. “People often sign these waivers not thinking they could actually die,” he says. “They signed a document that says they could, but their mind doesn’t go that far.”

When asked about the safety of the Titan submersible last year, Stockton Rush, OceanGate’s CEO, told CBS’s Pogue the risk was simply a part of life.“You know, there’s a limit. At some point safety just is pure waste. I mean if you just want to be safe, don’t get out of bed. Don’t get in your car. Don’t do anything. At some point, you’re going to take some risk, and it really is a risk/reward question.”

—With reporting by Anna Gordon/London

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