Secret US Navy listening devices detected an “anomaly” near the Titanic shipwreck soon after the Titan departed from its support ship the Polar Prince, which is believed to be the moment sub suffered a “catastrophic implosion” of its carbon fibre hull.

The source of the banging sounds has not been identified, but experts have put forward several theories about their possible origin.

On 22 June, Carl Hartsfield, an expert with the Wood Hole Oceanographic Institution, told CBS News there were many possible explanations for the sounds.

“The ocean is a very complex place, obviously — human sounds, nature sounds, and it’s very difficult to discern what the sources of those noises are at times,” he told the news site.

Jeff Karson, professor emeritus of earth and environmental sciences at Syracuse University, told Mail Online while the search was underway that the noise could be a “complicated echo” coming from sounds bouncing around the Titanic debris field.

“It’s just not bouncing off of one thing. It’s bouncing off a bunch of things. And it’s like, you know, dropping up a marble into a tin can. It’s rattling around and that would confuse the location,” he told the publication.

Stefan Williams, a professor of marine robotics at the University of Sydney, told Insider the sounds may have been created by marine wildlife such as whales.

He said there had been reports of marooned submarine crews banging on the vessel’s hull to signal their location, and that “acoustic noise will travel”.

RMS Titanic Inc, the organisation that provides educational information and preserves artifacts of the Titanic ,opened an online guestbook for Paul-Henri Nargeolet who was the director of underwater research.

“In loving memory of PH Nargeolet. Always in our hearts and thoughts. A true explorer of his time,” RMS Titanic Inc wrote in the introduction.

Hundreds of people left their memories of Mr Nargeolet as well shared their condolences to Mr Nargeloet’s family.

Even before the loss of the five passengers aboard the Titanic sub, psychologists have studied the rise in wealthy individuals embarking on extravagant yet dangerous adventures, and the reasons why these avid travellers are so intrigued by the thrilling experiences.

Speaking to The Independent, Dr Scott Lyons, a psychologist based in New York, explained how travelling can be used as a method of masking one’s negative feelings, such as boredom or sadness, with something exciting and adventurous.

But, according to Dr Lyons, when it comes to billionaires in particular, the trips required to distract from the tedium are often more frequent and extravagant.

“They’ve reached certain pinnacles in their professional life or social life where they kind of need more to feel more. To get that excitement or to ultimately feel alive,” he explained. “Travel, in particular, is one of the more accessible ways to get those thrills. Doing something that’s a ‘risky business’ adventure takes a lot more planning in some ways than going to say: ‘Oh we’re going to hike Mount Kilimanjaro.’”

Amber Raiken reports:

In a statement released on Sunday, the US Coast Guard announced a Marine Board of Investigation will work to better understand how the Titan submersible imploded.

A Marine Board of Investigation is the highest level of investigation in the Coast Guard.

“Upon completion of the investigation, the Board will issue a report to the Commandant with the evidence collected, the facts established, its conclusions, and recommendations,” the Coast Guard said.

Some of the questions they will seek to answer are:

- What was the cause of the casualty including any deaths?

- Did an act of misconduct, incompetence, negligence, unskillfulness, or willful violation of law committed by any individual licensed, certificated, or documented has contributed to the cause of the casualty, or to a death involved in the casualty?

- Did an act of misconduct, incompetence, negligence, unskillfulness, or willful violation of law committed by any person, including an officer, employee, or member of the Coast Guard, contributed to the cause of the casualty, or to a death involved in the casualty?

- Is there evidence that an act subjecting the offender to a civil penalty under the laws of the US has been committed?

- Is there evidence that a criminal act under the laws of the United States has been committed?

- Is there a need for new laws or regulations, or amendment or repeal of existing laws or regulations, to prevent the recurrence of the casualty?

The Dawood Foundation held a prayer service would be held on Tuesday for Shahzada and Suleman Dawood, the father and son who were killed in the Titan implosion.

“In loving memory of our beloved sons,” the announcement for the memorial service said.

The prayer took place at 9.30am EDT (2.30pm UK time).

The company that operated the Titan closed its headquarters in Everett, Washington State, following the vessel’s implosion, which killed OceanGate CEO Stockton Rush and British billionaire Hamish Harding, French diver Paul-Henri Nargeolet, Pakistani businessman Shahzada Dawood and his teenage son Suleman Dawood.

The leasing agent said in a statement to The Seattle Times that the company would be closing indefinitely.

Secret US Navy listening devices detected an “anomaly” near the Titanic shipwreck soon after the Titan departed from its support ship the Polar Prince, which is believed to be the moment sub suffered a “catastrophic implosion” of its carbon fibre hull.

The source of the banging sounds has not been identified, but experts have put forward several theories about their possible origin.

Bevan Hurley reports:

The US Coast Guard says the priority in its investigation into the fatal Titanic submersible implosion is the “recovery of items from the sea floor”.

Captain Jason Neubauer, chief investigator with the US Coast Guard, told reporters on Sunday, that: “My primary goal is to prevent a similar occurrence by making the necessary recommendations to enhance the safety of the maritime domain worldwide.”

A remotely operated vehicle (ROV) discovered debris from the Titan around 1,600ft from the bow of the liner days after it lost contact with its mother ship around 1 hour and 45 minutes into the dive.

Pelagic Research Services, the company that owns the ROV, tweeted pictures of the Titan recovery mission on Sunday.

A 20-year-old man who had a lucky escape from the doomed Titanic sub disaster has revealed how he turned down his father’s offer of a “bucket list” trip because he feared the vessel wasn’t safe.

Sean Bloom, 20, told People that he and his financier father Jay Bloom almost signed up to join OceanGate Expeditions’ tourist trip to visit the Titanic wreckage.

But, Mr Bloom said that he ultimately refused to go because he wasn’t convinced the Titan submersible would be able to withstand the pressure around 13,000 feet deep in the Atlantic Ocean.

“The whole reason my dad didn’t go was because I told him, ‘Dude, this submarine cannot survive going that deep in the ocean,’” Sean told People.

“I was worried because I didn’t think the submarine could withstand that kind of pressure and it wasn’t meant to go that far.”

He added: “That is a small submarine, with five people crammed inside. It just felt super unsafe. Something was telling me this was not the move.”

Ultimately, the Blooms decided against the trip and the final two seats were snapped up by a different father and son duo: Shahzada and Suleman Dawood.