Search-and-rescue efforts are underway to find a vessel that took five tourists to explore the Titanic shipwreck on Sunday — but has since gone missing.
The vessel is called Titan and is owned by OceanGate Expeditions, a company that takes passengers to see the Titanic wreckage for $250,000 each. Titan can carry five people to a depth of 13,123 feet, according to the company's website.
Notably, Titan is a submersible, not a submarine.
This means that it is launched from a support ship, which takes the vessel to the site where it will deep dive, similar to how a boat deposits a scuba diver into an area of the ocean to explore.
A submersible is smaller than a submarine and does not have the power to get to a port. It also needs a mothership to help recover it.
Submarines, on the other hand, can launch themselves into the ocean from a port independently, according to the National Oceanic and Atmospheric Administration.
OceanGate hired the Polar Prince to take the submersible craft to the Titanic wreck site. According to AP, the submersible was designed to make several dives in one expedition.
Titan was designed to be piloted with a video game controller and fitted with "off-the-shelf" components, according to a CBS News TV segment first released in November that featured the submersible, its mother ship, and crew.
The interior of the Titan is no bigger than a minivan and can accommodate around five people sitting cross-legged, as well as several screen displays and some camera equipment, CBS News reported.
The vessel is sealed with at least 17 deadbolts, which means the only way to get people out is to find and open it up.
"We only have one button, that's it. It should be like an elevator, it shouldn't take a lot of skill," said Stockton Rush, the CEO of OceanGate Expeditions — who is reported to also be on Titan — told CBS News in the video.
Marine scientist Peter Girguis says submersibles are actually more reliable with simple hardware.
Alistair Greig, a professor of marine engineering at University College London, told AP submersibles typically have a drop weight, which is "a mass they can release in the case of an emergency to bring them up to the surface using buoyancy."
"If there was a power failure and/or communication failure, this might have happened, and the submersible would then be bobbing about on the surface waiting to be found," he said.
Titan's location is unknown because it lost contact with its support ship, Polar Prince, as CNN reported.
As OceanGate told the BBC, Titan's dive began on Sunday after Polar Prince escorted the submersible to the site of the Titanic wreckage, which is near Newfoundland, Canada. The submersible lost contact with Polar Prince less than two hours into its journey.
Five passengers were on board Titan for its dive, and the vessel is equipped with life support for those passengers for 96 hours from the time of departure, according to OceanGate's website. The US Coast Guard estimates the missing sub's oxygen supply is somewhere between the full 96 hours and only 70 hours.
The US Coast Guard is carrying out search-and-rescue operations to attempt to find the submersible, with Rear Admiral John Mauger of the US Coast Guard saying the "remote" location of the site is making the efforts more difficult.
"It is a remote area and it is a challenge to conduct a search in that remote area, but we are deploying all available assets to make sure that we can locate the craft and rescue the people on board," he said, according to The New York Times.
