(Spanish CNN) — The US Coast Guard has launched an intensive search to find and rescue the five people aboard Titan, the submarine that went missing during an expedition to the wreckage of the Titanic at the bottom of the Atlantic Ocean.

This submersible, which can carry up to five people, offers a voyage to the depths of the ocean to see first-hand the remains of the famous ocean liner that sank in 1912 off the coast of Newfoundland, Canada.

OceanGate Expeditions, the company running the tour, described the tour as a way to “get out of the ordinary and experience something truly extraordinary,” according to an archived version of its website, available at Internet Archive’s Wayback Machine.

Among the people on board the expedition, with whom contact was lost this Sunday morning after 1h45 of underwater descent, is the British businessman Hamish Harding, according to a publication on the social networks of his company, Action Aviation.

“I am proud to finally announce that I have joined OceanGate Expeditions for their RMS TITANIC mission as Mission Specialist on the Titanic Submarine,” Harding wrote in a Facebook post on Saturday. CNN contacted Action Aviation for comment, but did not immediately respond.

The US Coast Guard is now doing “everything possible” to locate and rescue those aboard the missing submersible, Rear Admiral John Mauger said Monday at a press conference.

How is the Titan, the submarine that disappeared during the tourist expedition to the remains of the Titanic? That’s what we know.

Aboard the Titan, the submarine that travels to the remains of the Titanic in the depths of the ocean

Undated photograph of the Titan submarine. (Credit: OceanGate/File)

The expedition to see what remains of the Titanic up close starts from the town of St. Johns, in the Canadian province of Newfoundland.

There, according to OceanGate Expeditions, up to five people board the submersible and descend into the depths of the ocean. The journey begins with a 400 nautical mile journey to the shipwreck site.

Among those traveling on board are a pilot, a “content expert” and three paying passengers for the ride.

The archived version of OceanGate’s website explains what passengers can expect from the trip, which costs $250,000.

“Follow in the footsteps of Jacques Cousteau and become an underwater explorer, starting with a dive on the wreck of the RMS Titanic. This is your chance to step out of the ordinary and discover something truly extraordinary,” says the website. “Become one of the few to see the Titanic with your own eyes.”

According to OceanGate, the Titan is a submersible just over 10 tons made of carbon fiber and titanium. As a safety measure, the submarine uses a “proprietary real-time hull health monitoring (RTM) system” that analyzes the pressure in the vessel and the integrity of the structure, the company says. It also has a life support system for a crew of five for 96 hours, according to the website.

A complex search

John Mauger, Rear Admiral of the US Coast Guard, said the search for crew members aboard the Titan is complex and taking place in a remote location, both underwater and on the surface.

Mauger recalled that the submersible has 96 hours of emergency oxygen on board, according to information received from the ship’s operator.

The Coast Guard “estimates there are between 70 and 96 hours” of oxygen available on the submarine at this time, he said at a Monday news conference.

The crew of the Polar Prince, which carried the Titan to the site of the Titanic wreckage before it plunged to the depths of the ocean, lost contact with the submarine 1 hour 45 minutes after it descended on Sunday morning , the US Coast Guard reported.

For its part, OceanGate Expeditions appreciated the help received from the authorities in trying to restore contact with the submersible. “Our full attention is focused on the crew members and their families,” the company said in a statement. “We are working to get the crew members back safe and sound.”

CNN’s Eric Levenson, Raja Razek, Paul P. Murphy, Tanika Gray, Kristina Sgueglia contributed to this report.