The Titanic submarine, which is currently missing in the mid Atlantic has lost communication before, according to one of its former passengers.
A huge search and rescue operation is under way after OceanGate's Titan lost contact during a dive to the ship's wreck on Sunday.
On Monday afternoon, passengers on board the craft were estimated to have between '70 and the full 96 hours of oxygen available.'
However, former US nuclear submarine commander David Marquet believes there is now less than a one per cent chance of the crew surviving "if they are on the bottom".
Mike Reiss took the same journey to the Titanic last year and says he's 'not optimistic' about the submarine being located.
Speaking about the crew's chances of survival, he told BBC Breakfast: "I'm not optimistic just because I know the logistics of it.
"I did three separate dives and every time they lost communication. This is not to say it's a shoddy ship but this is all new technology."
Mike's interview didn't go down well with some as viewers accused him of being tactless towards the crew's family.
One tweeted: "Whilst Mike is happily telling his adventure stories 5 people are stuck in a submarine facing death somewhere at the bottom of a very deep ocean. I cannot imagine how frightened & isolated they must be feeling!"
While another fumed: "This guy Mike is smirking and smiling about his trip while the families of five humans anxiously await the safe return of their loved ones!! This is so so disrespectful!"
Rear Admiral Mauger, who is part of the search, said two aircraft, a submarine and sonar buoys were looking for the vessel, but pointed out the area in which the search is taking place was "remote", making things difficult.
However he also said the rescue teams were "taking this personally" and were doing everything to bring those on board "home safe".
Hamish Harding, a 58-year-old British billionaire businessman and explorer, is among those on the missing submarine, his family said.
On social media at the weekend, Mr Harding said he was "proud to finally announce" he would be aboard the submarine to see the Titanic - but added that because of the "worst winter in Newfoundland in 40 years, this mission is likely to be the first and only manned mission to the Titanic in 2023".
He later wrote: "A weather window has just opened up and we are going to attempt a dive tomorrow."
As the search continues, OceanGate said its "entire focus [was] on the crew members in the submersible and their families".
