The more I read about the rich person submersible (coffin tube) The less I'm hopeful that the people in the tube sub will be found alive. Carbon fibre/ titanium casing? Low return on sonar and acoustics. It says life support.... but does that include air recycle and filtration?
Know what happens when you breathe in the same air without filtering it? You get less and less breathable air, and more a toxic airy sludge of respiratory byproducts.... like CO2, CO, and whatever off gasses (farts) from the digestive system, so there's that to consider...
This is the CuraSub from Nuytco Research Ltd..... a company that has been doing deep sea shit for decades.
Please note the differences in the tech sheet. Two pages, tells you all the tech that is on the submersible.
Can a CuraSub go to 4000m (14,000ish feet) below the surface? No. Can Nuytco build a submersible that can? Yes. They have before. Is it cheep? No. Also please note the hull thickness's between the two... the OceanGate tube, is about the same thickness as the CuraSub....
I'd rather take my chances in a Nuytco Research submersible than a private adventure company tube.