(NewsNation) — As some question the risks of the missing submersible touring Titanic wreckage, a man who has been on it says: “No one ever said it was safe.”

Fred Hagen is an explorer. He has made the journey to the Titanic wreck site twice aboard the OceanGate Expeditions Titan submersible that is now lost.

“No one ever said it was safe. (CEO) Stockton Rush didn’t say it was safe,” Hagen told NewsNation host Dan Abrams on Tuesday. “Everyone that participated signed an agreement or signed an acknowledgement that they could die or be grievously injured.”

Hagen does not believe Sunday’s trip to the Titanic was poorly planned. He thinks it was just an inherently risky operation.

“It was very dangerous. No one ever said it wasn’t. In fact, the opposite was true,” Hagen said. “We were told repeatedly (on my expeditions) that we could be facing death or serious injury if anything went wrong.”

David Pogue, the host of the “Unsung Science” podcast and a “CBS Sunday Morning” correspondent, tried to see the Titanic on the now-missing submersible last year for a story. Pogue said they got about 37 feet down when they ran into mechanical problems and had to return to the surface.

“But, that’s typical,” Pogue said on “NewsNation Now” on Monday. “They take these millionaires out there for five days at a time, so they have five chances to see the Titanic. Most weeks they make it only once or this summer, not at all.”

Pogue claims the submersible was “constantly plagued with mechanical problems” and did acknowledge the waiver.

“You know, it’s not going to be Delta Air Lines-level safety. You sign a waiver. It says these are the different ways I could die. They outline it for you,” Pogue told NewsNation host Elizabeth Vargas.

Search crews are now up against the clock as the lost submersible has around 40 hours left of breathable air for the five people inside. Hagen thinks calling those on the submersible tourists is a mischaracterization.

“It’s not a tourist. These are serious people that want to contribute to the science of deep ocean exploration. They’re contributing their funds and their time and their resources to do so,” Hagen said.

He continued: “If we were unable to accept risk as a society, we would still be paddling canoes in open water, we would never learn to sail across oceans, we would never have gone in outer space. It’s just risky.”

The Titan takes people paying thousands of dollars each to view the remains of the Titanic.

The missing submersible is believed to be about 900 miles east of Cape Cod. Locating the vessel is just part of the challenge rescue teams face. Officials may also need to figure out how to bring the submersible, which could be as far as two miles underwater, to the surface.

As of Tuesday morning, a total of 10,000 square miles had been searched for the missing 21-foot submersible. To put it into perspective, NewsNation host Leland Vittert said it’s like rescuers have less than 40 hours to find a penny in an area the size of 60 football fields.

The Titanic wreckage is about 12,000 feet at the bottom of the Atlantic Ocean off the coast of Newfoundland, Canada. The ship sank in 1912 after hitting an iceberg.