A five-passenger OceanGate Expedition submarine that set out to explore the iconic Titanic shipwreck has disappeared. And the search has become more desperate since the missing passengers are running out of oxygen. 

David Concannon, a company adviser said the company lost contact with the tourist submarine on Sunday morning.

It only has a 96-hour oxygen supply, he said on Monday afternoon. "Now 32 hours since sub left surface," said Concannon. He also claimed he was supposed to be on the dive, but could not go due to other obligations.

OceanGate officials are working to get a remotely operated vehicle that can reach a depth of 6,000 meters (about 20,000 feet) to the site before the oxygen supply runs out.

The United States Coast Guard in Boston is leading the search and rescue operations. Lt. Cmdr. Len Hickey confirmed a Canadian Coast Guard vessel and military aircraft were assisting the efforts.

 The Joint Rescue Coordination Centre in Halifax, Nova Scotia said the vessel was reported overdue around 9:13 p.m. Sunday.

U.K. businessman and Action Aviation chairman, Hamish Harding, was one of the tourists on board. 

The company’s managing director, Mark Butler said that "Every attempt is being made for a rescue mission. There is still plenty of time to facilitate a rescue mission, there is equipment on board for survival in this event." 

"We’re all hoping and praying he comes back safe and sound," Butler added.

OceanGate Expedition takes tourists to the Titanic 

OceanGate Expeditions, is a private company offering exclusive tours of the historic Titanic site.

Resting approximately 12,500 feet below the ocean's surface off the coast of Newfoundland, Canada lies the wreckage of the Titanic.

This tragic shipwreck is situated around 370 miles away from land. And serves as a haunting reminder of the ship's ill-fated maiden voyage in April 1912. 

The "unsinkable" vessel collided with an iceberg, claiming the lives of over 1,500 passengers and crew members during its journey from Southampton, England, to New York.

OceanGate's expeditions offer tourists a rare opportunity to venture into the depths of the Atlantic and view the tragic resting place of the Titanic. The submersible dives, last up to 10 hours each.

The expedition relies on Elon Musk's Starlink satellites for communication during the trips.

Tickets for this extraordinary experience can command prices as high as $250,000, attracting a niche group of passionate enthusiasts. 

OceanGate's CEO Stockton Rush acknowledges the enduring allure of the Titanic, referring to its dedicated fanbase as "Titaniacs" who spare no expense to partake in this extraordinary journey.

The recent release of over 700,000 scans and stunning 3D reconstructions of the wreckage by Atlantic Productions and Magellan Ltd. serves as a testament to the enduring fascination with this tragic event.

The search for the missing submarine is ongoing.