Former Titan submersible passenger who visited the Titanic said he knew he might die and that 'nobody walked into this thinking it was going to be a pleasure cruise'

• Mike Reiss visited the Titanic last year in OceanGate's Titan submersible.
• Reiss said he knew he could die when he kissed his wife goodbye before the dive.

A former passenger of the Titan submersible who visited the Titanic shipwreck last year said he knew he might die and that the five missing people would've also understood the risks.

The Titan has been missing since Sunday, when it lost contact with its surface vessel less than two hours into the dive, kicking off a major search-and-rescue effort for the submersible and the people on board.

Mike Reiss, a writer and producer for "The Simpsons," told CNN that he knew the stakes were high when he took the same voyage in OceanGate Expeditions' Titan submersible to visit the Titanic last year. Reiss said he had to sign a waiver beforehand that mentioned several times he could die.

"In every way, it felt like being a Mercury astronaut," Reiss said. "This wasn't a vacation. It wasn't tourism. It was exploration. And you're getting on a ship that's the best it could be, but they're learning as they go along.

"You get on with a lot of excitement but just constant trepidation, constantly knowing this could be the end."

Reiss said he and his wife were supposed to go on the voyage together but that she tested positive for COVID-19 and had to stay behind.

"I kissed her goodbye knowing that that might be the last time I'd ever see her," he said, adding: "Nobody walked into this thinking it was going to be a pleasure cruise, especially the experts involved."

He noted Stockton Rush, the CEO of OceanGate, the company behind the trip, was also in the submersible when it went missing.

"They made it as safe as they could make it. They trusted their own lives to it," Reiss said, "but they knew it could end this way."

On Monday, the US Coast Guard estimated the submersible had 70 to 96 hours of oxygen left, which would mean it could last until Thursday afternoon ET.