As efforts to locate the missing Titanic-exploring submersible continue, former passengers are sounding off about their experience with OceanGate's Titan sub, with one labeling the adventure as a "suicide mission."

"It was a suicide mission back then!" retired businessman and adventurer Arthur Loibl, 61, told German outlet Bild. 

In August 2021, Loibl participated in the underwater adventure, but shared that the experience was "extreme."

"The first submarine didn’t work, then a dive at 1,600 meters had to be abandoned," he said, noting that his group ended up launching five hours later due to electrical issues. 

MISSING TITANIC SUB ‘DID NOT PERFORM WELL,’ SAYS VETERAN EXPLORER WHO NIXED DOCUMENTARY OVER SAFETY CONCERNS

Arthur Loibl

Arthur Loibl, a former passenger on the Titan, was one of the first passengers to descend to the Titanic in a mini-submarine operated by OceanGate Expeditions. (Armin Weigel/picture alliance via Getty Images)

Along with the nerve-wracking delay, the bracket of the stabilization tube – which balances the sub – tore and had to be "reattached with zip ties," he said. 

"That didn't worry me," Loibl added.

Arthur Loibl in front of submersible

Loibl was one of three explorers to descend into the Atlantic Ocean in an OceanGate Expeditions sub to view the Titanic wreckage. (Armin Weigel/picture alliance via Getty Images)

He described the conditions the passengers are facing onboard the missing Titan submersible as "hell."

"You need strong nerves, you mustn't be claustrophobic, and you have to be able to sit cross-legged for ten hours," Loibl said. "It must be hell down there. There's only 2.5 meters of space, it's four degrees, there's no chair, no toilet."

The sub, which is carrying five passengers, measures about 22 feet long and 9.2 feet wide, according to OceanGate's website.

NEW ASSETS ‘ON-SCENE’ IN MISSING TITANIC SUBMARINE SEARCH AFTER CANADIANS PICK UP ‘UNDERWATER NOISES’

"It must be hell down there."

— Arthur Loibl

Another thrill-seeker placed the deposit for the $250,000 trip to the ocean's depths, but he backed out over "safety concerns."

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"Being a modern-day adventurer interested in pushing the boundaries of our knowledge of places that people go... the Titanic is obviously an iconic wreck," Chris Brown told Good Morning America. "It's a chance for an expedition, an exploration and adding a bit of science into the situation."

OceanGate Titan sub

OceanGate's Titan submersible has been missing since Sunday with five passengers onboard. (OceanGate Expeditions)

Brown, 61, dropped out after becoming concerned over the quality of technology and materials used by the company, but declined to comment on the specifics of the safety features that he saw as red flags.

In a video interview in 2022, OceanGate CEO Stockton Rush revealed that the sub is operated by a game controller that currently retails on Amazon for $30. 

In his "CBS Sunday Morning" interview, Rush showed the remote controller that appeared to have elongated, modified sticks to help control the Titan sub. 

Logitech F710 video game controller and OceanGate Titan sub

The Logitech F710 video game controller operates the OceanGate Titan submersible, according to CEO Stockton Rush. (Joby Sessions/PC Gamer Magazine/Future via Getty Images/OceanGate Expeditions)

While declining to comment any further, Brown acknowledged that adventurers like himself sometimes fail to consider how their actions impact their loved ones. 

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"We fully understand the risk and take them onboard," he said. "But [friends and family] haven’t been so involved in the process...in a situation like this, it’s probably as if the bottom has dropped out of their worlds."