- Friends and family members are discussing the motivations of Titan's passengers.
- Five people died on the submersible, including father and son Shahzada and Suleman Dawood.
The family of Suleman Dawood, the 19-year-old who died with his father in the Titan submersible, have given conflicting accounts of whether he wanted to join the doomed trip.
The Titan submersible, run by OceanGate Expeditions, suffered a catastrophic implosion that instantly killed all five passengers, according to US authorities.
Three of the passengers - Stockton Rush, the CEO of the company that owned the submersible, explorer Hamish Harding, and Paul-Henri Nargeolet - were seasoned explorers.
The remaining two passengers, Shahzada Dawood, a British-Pakistani businessman, and his son Suleman, had less experience on perilous missions.
On Sunday, Suleman's mother, Christine Dawood, told the BBC that she had initially been booked onto the Titan's trip, but stepped aside because her son had been keen to join.
She said Suleman was intent on breaking the world record for the depth at which a Rubik's cube puzzle had been solved.
"He said, 'I'm going to solve the Rubik's Cube 3,700 metres below sea at the Titanic'," she recalled.
She said she had been present with her daughter on the Titan's mothership during the expedition, and the family had embraced and made jokes before her husband and son boarded the submersible.
"I was really happy for them because both of them, they really wanted to do that for a very long time," she said.
Shahzada Dawood was vice-chairman of Pakistani conglomerate Engro Corporation, a fertilizer firm, and also supported a range of charities. His son was a business student at the University of Strathclyde in Scotland.
Tributes to the pair have flooded in from family members and friends since news of the Titan's fate broke.
In an interview last week when the huge search-and-rescue operation for the missing vessel was underway, Suleman's aunt, Azmeh Dawood, had offered a contrasting account of her nephew's state of mind leading up to the trip.
Suleman "wasn't very up for it" and felt "terrified" about making the trip to the sunken ship, she told NBC News.
She claimed he'd taken part in the trip to please Shahzada during the Father's Day weekend, with his father a longtime Titanic lore devotee.
The report described Azmeh as partly-estranged from her brother, who it said disapproved of her use of medical cannabis, but was still close to her nephew.
Richard Hawkes, a friend of Shahzada, told the BBC that he would never have put his son's life at risk if he'd been aware of longstanding safety concerns about the vessel.
"I can't imagine that Shahzada would have done anything that he thought possibly could have had the devastating consequences that we've seen this week," Hawkes said.
"The children absolutely loved him and they did lots of interesting things together. It's just an absolute tragedy that this one has ended up in this way."
In a statement to People magazine after remains of the wreckage were found Thursday, indicating it imploded, the Dawood family paid tribute to the close bond between father and son.
"The relationship between Shahzada and Suleman was a joy to behold; they were each other's greatest supporters and cherished a shared passion for adventure and exploration of all the world had to offer them," it said.