7 reasons why we now know going on the Titan sub was a very bad idea

• Five people died in June after the Titan submersible imploded on a dive to see the Titanic.
• Many safety concerns relating to the sub have been brought to light since the tragedy.

Five people on OceanGate's Titan submersible died when it imploded in June.

The sub was on an expedition to the Titanic wreckage, which sits nearly 13,000 feet below the ocean surface, when it lost communications with its support ship an hour and 45 minutes into the trip.

US Coast Guard officials said the sub probably suffered a "catastrophic loss of the pressure chamber."

In the weeks following the incident, multiple reports appeared detailing significant concerns that had surrounded the sub long before its fateful final journey — many of which passengers may have been unaware.

Here's seven reasons why we now know going on the Titan sub was a very bad idea.

1. The Titan sub was not certified by regulatory bodies

Former OceanGate consultant Rob McCallum warned CEO Stockton Rush in 2018 that he was putting passengers in danger and urged him not to carry out expeditions until the sub was proven to be safe.

"Until a sub is classed, tested and proven it should not be used for commercial deep dive operations," McCallum told Rush in an email reviewed by Insider.

OceanGate said in an archived blog post that getting the Titan classed would be a lengthy process, which could stifle innovation.

"Bringing an outside entity up to speed on every innovation before it is put into real-world testing is anathema to rapid innovation," OceanGate said in the 2019 post.

2. The sub only reached the depth of the Titanic on 13 out of 90 dives

The Titan submersible had successfully reached the depth of the Titanic wreck on "as few as 13" out of 90 dives, according to OceanGate's four-page liability waiver, which also describes the sub as "experimental" three times.

3. OceanGate's approach to engineering was "ad hoc"

McCallum told Insider in June that OceanGate's engineering approach was "ultimately inappropriate." The former consultant said the differences between OceanGate and other submersible operators' engineering standards were "profound".

"Comparing Titan to the commercial fleet is the same as comparing a home-built go-kart with a Formula 1 car," he said.

4. An expert heard a "defect" in 2019

Karl Stanley, a submersible expert who was a friend of Stockton Rush, told NewsNation he heard "cracking" sounds when he went on the sub in April 2019 and emailed Rush about his concerns.

"What we heard, in my opinion … sounded like a flaw/defect in one area being acted on by the tremendous pressures and being crushed/damaged," Stanley told Rush in emails seen by CNN.

5. OceanGate's liability waiver mentions death numerous times

The waiver, signed by a prospective passenger, lists all the ways people could be at risk of harm and mentions "death" three times on the first page.

The risks of death stated in the document include from "extreme pressure," "unpredictable" conditions, from boarding "small vessels and other equipment," or any other failure of the sub.

It also included being exposed to high-pressure gasses, pure oxygen servicing, and high-voltage electrical systems.

6. Titan failed a test dive in 2021

It failed a test dive in 2021 because its thrusters stopped working, Brian Weed, a former passenger, told Insider

He added that it was stuck underwater for more than two hours and never made it deeper than 100 feet.

Tests on the sub also found that its carbon-fiber hull "showed signs of cyclic fatigue" at lower depths, according to GeekWire.

7. Inadequate "quality control and safety" protocols

OceanGate's former director of marine operations, David Lochridge, sued the company in 2018 after he raised a number of red flags over the sub.

He warned the company's management about inadequate "quality control and safety" protocols and said he had major concerns about the lack of testing on the hull.

Lochridge claimed in the lawsuit he was then fired and accused of breach of contract. The case was reportedly settled out of court in November 2018.

OceanGate did not immediately respond to a request for comment from Insider, made outside normal working hours.