What about the Titanic, the submarine that disappeared while heading for the wreck of the Titanic?

(CNN Spanish) — The US Coast Guard has launched an intensive search to locate and rescue five people aboard the Titanic, a submarine that went missing during a trip to the wreck of the Titanic on the bottom of the Atlantic Ocean.

This five-person submarine offers a journey into the depths of the ocean to see first-hand the remains of the famous ocean liner that sank off the coast of Newfoundland, Canada in 1912.

OceanGate Expeditions, the company that operates the tour, described the tour as a way to “step out of the ordinary and discover something truly extraordinary,” according to an archived version of its website. The Internet Archive’s Wayback Machine.

Among those on board, British businessman Hamish Harding lost contact after being submerged for 1 hour and 45 minutes this Sunday morning, according to a release on his company’s social networks, Action Aviation.

“I am proud to finally announce that I have joined OceanGate Expeditions as a mission specialist on the Titanic submarine for their RMS TITANIC mission,” Harding wrote in a Facebook post on Saturday. CNN Action Aviation reached out to the company for comment, but did not immediately hear back.

Now, the US Coast Guard is doing “everything possible” to find and rescue those aboard the missing submarine, Rear Admiral John Mauger said at a press conference on Monday.

What about the Titanic, the missing submarine, on a tour of the remains of the Titanic? This is what we know.

In Titan, a submarine travels towards the remains of the Titanic in the depths of the ocean

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

The tour begins from St. John’s in the Canadian province of Newfoundland to see the remains of the Titanic.

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

The crew includes a pilot, a “content expert” and three passengers who pay for the tour.

An archived version of OceanGate’s website explains what passengers can expect from the $250,000 cruise.

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

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

A complicated search

U.S. Coast Guard Rear Admiral John Mauger said the search for the Titan’s crew was complex, both underwater and on the surface.

According to information received from the ship’s operator, Mauger recalled that the submarine had 96 hours of emergency oxygen.

The Coast Guard estimates the submarine has 70 to 96 hours of oxygen at this point, he said during a press conference Monday.

The crew of the Polar Prince, which took the Titanic to the site of the Titanic’s wreckage before sinking into the ocean, lost contact with the submarine 1 hour and 45 minutes after disembarking Sunday morning, the US Coast Guard said.

For its part, OceanGate Expeditions appreciated the help it received from authorities in trying to re-establish contact with the submarine. “All our attention is focused on the team members and their families,” the company said in a statement. “We are working to ensure the safe return of crew members.”

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