The submersible that was reported missing while on a tour of the underwater wreckage of the Titanic is an unorthodox vessel with a relatively unproven history, according to company press materials and experts familiar with underwater vehicles.

News of the vessel's disappearance prompted a flurry of interest in the company OceanGate Expeditions and its deep-sea submersible called the Titan.

The company's founder and CEO, Stockton Rush, who is one of the five people aboard the missing vessel, manned the Titan's first "validation dive" to 4,000 meters in 2018, according to the company. The company then began offering tourists the opportunity to dive to the depths of the Titanic in the following years, selling tickets for the 2023 journey for $250,000.

Here's what we know about how the submersible operates.

-ABC News' Peter Charalambous

A source familiar confirmed to ABC News that there were reports of "banging" that were picked up by sonar in the search area on Tuesday morning, but nothing has yet been found.

The U.S. Coast Guard had said early Wednesday that an aircraft with sonar capability "detected underwater noises in the search area," but remotely operated vehicles were unable to find the origin of the sound.

-ABC News' Luke Barr

Magellan, an international exploration company that digitally mapped the Titanic wreckage last year, said Wednesday that it is "ready to support" the search for the missing submersible and is "fully mobilized to help."

The U.K.-based company told ABC News that it was contacted by the submersible’s operator, OceanGate Expeditions, early Monday and "immediately offered our knowledge of the specific site and also our expertise operating at depth considerably in advance of what is required for this incident."

"We have been working full-time with U.K. and U.S. agencies to secure the necessary air support to move our specialist equipment and support crew," Magellan said in a statement.

When asked for comment about media reports that U.S. authorities have failed to give Magellan the necessary permits to participate in the search, the company told ABC News it "does not not wish to comment on any specific media report."

-ABC News' Emma Ogao

The U.S. Coast Guard announced via Twitter early Wednesday that a Canadian aircraft with sonar capabilities had "detected underwater noises in the search area."

Remotely operated vehicle operations (ROV) were then relocated "in an attempt to explore the origin of the noises," according to the Coast Guard.

"Those ROV searches have yielded negative results but continue," the Coast Guard tweeted.

One of the ships the Canadian Coast Guard sent to the rescue effort, the John Cabot, is equipped with advanced, deep sonar, said Joyce Murray, minister of Fisheries, Oceans and the Canadian Coast Guard.

"We've sent so many assets to the search team to help," Murray said. "Authorities still have hope in the mission."

-ABC News' Will Gretsky