"Search for Missing Titanic Sub Comes to Tragic End"

The missing submersible, Titan, used by OceanGate Inc. for deep-sea tours of the Titanic wreckage, communicates using underwater sounds and navigates using a 2D sonar and Doppler velocity log. The submersible is operated using a PlayStation game controller and has a cylinder shape with a carbon fiber body sealed with two titanium caps. The vessel's pressure hull is monitored for health, and the hinged hatch is bolted shut externally, making it impossible for occupants to open the door from inside the craft when the vessel surfaces.