(NewsNation) — A rescue mission is underway after a tourist submarine carrying people to see the wreckage site of the Titanic went missing in the Atlantic Ocean on Monday.
This is what we know about the submarine vessel and its crew.
The Titanic expedition
In 2021, OceanGate Expeditions began what it expected to be an annual voyage to track the rate of decay of the Titanic, according to the tour group’s website.
The purpose of the Titanic expedition is to chronicle the decay of the iconic ocean liner that sunk in 1912 after hitting an iceberg, killing all but about 700 of the 2,200 passengers and crew onboard. The ship’s wreckage was discovered in 1985 and has been slowly deteriorating to metal-eating bacteria.
The OceanGate Expedition’s tour departs from St. Johns, Newfoundland, in Canada, and travels about 380 nautical miles south. The trip was scheduled to depart in early May and finish up by the end of June.
Tickets for the five-person submarine cost $250,000 a seat, with the vessel being the only one of its size capable of reaching the Titanic wreck.
Submarine Specs
The five-person vessel, called the Titan, weighs about 23,000 pounds on land, but is neutrally buoyant once it reaches the seafloor, OceanGate Expedition said.
The Titan is made of carbon fiber and titanium and can reach depths of more than 13,000 feet.
The vessel is equipped with sophisticated technology including a “proprietary real-time hull health monitoring system (RTM)” that analyzes the pressure on the vessel and the integrity of its structure.
Oxygen Supply
According to the OceanGate Expedition website, the vessel is equipped with 96 hours of life support for a five-person crew.
It is currently unclear how much of that supply is remaining for the crew onboard.
Just how deep would the submarine have to go to reach the wreck of the Titanic? 
A map shows the search area as the Coast Guard looks for a missing submarine 
FILE – This 2004 photo provided by the Institute for Exploration, Center for Archaeological Oceanography/University of Rhode Island/NOAA Office of Ocean Exploration, shows the remains of a coat and boots in the mud on the sea bed near the Titanic’s stern. A search is underway for a missing submersible that carries people to view the wreckage of the Titanic, according to media reports. The U.S. Coast Guard told BBC News that a search was underway Monday, June 19, 2023, off the coast of Newfoundland. (Institute for Exploration, Center for Archaeological Oceanography/University of Rhode Island/NOAA Office of Ocean Exploration, File) 
In this grab taken from a digital scan released by Atlantic/Magellan on Thursday, May 18, 2023, a view of the bow of the Titanic, in the Atlantic Ocean created using deep-sea mapping. Deep-sea researchers have completed the first full-size digital scan of the Titanic wreck, showing the entire relic in unprecedented detail and clarity, the companies behind a new documentary on the wreck said Thursday. (Atlantic/Magellan via AP) 
Underwater photo shows wreckage of Titanic. (AP)