WATCH: Teenager on tragic Titanic submersible solved Rubik's Cube in 20 seconds; wanted to break work record

The youngest Titanic submersible catastrophe victim brought his Rubik's Cube because, according to his mother, he planned to set a world record for solving it underwater. Suleman Dawood, 19, and his father Shahzada, as well as Stockton Rush, 61, the CEO of OceanGate, the company that owned the Titan, Hamish Harding, 58, and Paul-Henry Nargeolet, 77, perished in the catastrophe last week.

Also read: Doomed Titanic submersible explainer: What is an implosion, was it preventable, what happens next and more

Christine, Suleman's mother, and Alina, his sister, were both on board the Polar Prince throughout the entire tragedy. They didn't come back to land until the Polar Prince anchored on Saturday, eight days after leaving port. According to Christine, a native of Long Ditton, Surrey, she had first intended to visit the Titanic disaster with her husband. But the Covid epidemic forced the cancellation of an earlier planned trip.

Suleman and Shahzada gave Christine and Alina a final embrace and joked with them just before they climbed aboard the submersible. And Christine revealed her son - capable of completing Rubik's Cube in 12 seconds - had contacted Guinness World Records before setting off.

WATCH: Suleman Dawood solve Rubik's Cube in 20 seconds:

"I was really happy for them because both of them, they really wanted to do that for a very long time. He said, 'I'm going to solve the Rubik's Cube 3,700 meters below sea at the Titanic'," Christine told BBC in an interview. 

"I think I lost hope when we passed the 96 hours mark," she added.

Christine continued by saying that her husband, who is the son of one of Pakistan's richest billionaires, has a contagious curiosity about everything. She said that's when she sent a message to her family. "I said: 'I'm preparing for the worst.' That's when I lost hope."

Also read: US tycoon turned down cheap tickets on doomed Titanic submersible; shares chilling texts with Stockton Rush

The Royal Canadian Mounted Police announced they are investigating the circumstances surrounding the deaths of the passengers. Former Navy doctor Dr. Dale Molé asserts that the crew of the submarine would have experienced a swift and painless death.

"It would have been so sudden, that they wouldn't even have known that there was a problem, or what happened to them. It's like being here one minute, and then the switch is turned off. You're alive one millisecond, and the next millisecond you're dead," he stated.

He explained that the team would not have been aware of the issue or what was taking place to them.

On Thursday, pieces of the OceanGate Titan submersible were discovered around 1,600 feet (487 metres) from the Titanic wreck's bow. The submersible went missing on Sunday.

Also read: 5 dead after ill-fated Titanic submersible's 'catastrophic implosion'; major pieces of Titan found

• Titanic
• Titan
• OceanGate
• Suleman Dawood
• Shahzada Dawood
• Rubik's Cube