A search is underway for a missing submersible that carries people to view the wreckage of the Titanic. Canadian officials say the five-person submersible was reported overdue Sunday night about 435 miles (700 kilometers) south of St. John's, Newfoundland and that the search is being led by the U.S. Coast Guard. The owner of the ship that launched the submersible confirmed that it was operated by OceanGate Expeditions, which has been operating annual voyages since 2021 to the wreckage of the iconic ocean liner. In a statement, the company said it is working to bring the crew back safely.
But apparently they cannot open the hatch from the inside, so even if they are on the surface, the oxygen will still run out if they’re not found.
Edit: here’s an article about this: https://www.insider.com/people-missing-submersible-deadbolt-screws-airtight-coast-guard-2023-6
I assume there is also no vent or similar to let air in?