What's it really like 12,500 feet below the surface?
A passenger who previously rode on the missing Titanic research submersible is here to explain.
As Aaron Newman—an investor in OceanGate who toured the wreckage 350 miles off the coast of Canada in 2021—put it, the expedition as "basically going to another planet."
"You're getting in this craft—you're bolted in," he told Today on June 21. "It's a tube that's comfortable, but not spacious."
In the beginning, the submersible's cabin is "very hot and stuffy," but Newman said the water surrounding the vessel drops to 29 to 30 degrees Fahrenheit as it submerges deeper into the ocean.
"By the time you hit the bottom, the water down there is below what standard freezing temperature is," he explained. "That's going to conduct right through that metal, so it was cold when we were at the bottom. You had to layer up—we had wool hats on and were doing everything to stay warm at that bottom."
And though Newman felt "very safe" while riding in the sub, he noted "there are risks" in taking such a challenging expedition.
"This is not a Disney ride, right?" he remarked. "We're going places that very few people have been, and this is inventing things."
Newman added that the five passengers on the sub, missing since June 18, must have accepted these risks prior to their mission.
"None of these people were people that were I would consider tourists—tourists is such a bad term," he said. "These are people who lived on the edge and loved what they were doing and if anything's going on, these are people that are that are calm and thinking this through and doing what they can to stay alive. So this is a good set of people."
Since the 21-foot sub went missing, rescuers have been working around the clock to locate the watercraft, which officials estimate has less than 40 hours of oxygen left in its cabin.
Among the missing is British billionaire Hamish Harding and OceanGate CEO Stockton Rush.
"Our focus is just hoping for this Hollywood ending to happen," Newman said of the missing sub and its crew. "We know the Coast Guard and everybody else is working so hard. And the OceanGate crew is working as hard as they can to possibly find this if anything is out there."
He added, "It's promising but there's work to be done, and that's what the focus is."
Keep reading for more details on the missing passengers.
(E! and Today are both part of the NBCUniversal family.)