These 5 key vessels are playing a big role in the search efforts

Authorities said the Titan submersible was carrying five people when its mothership lost contact with it on Sunday, about 1 hour and 45 minutes into its descent to explore the Titanic wreckage. 

Here's what we know about the people on board:

Paul-Henri Nargeolet, a French diver with decades of experience exploring the Titanic, is on the vessel, according to his family.

Nargeolet serves as the director of underwater research at RMS Titanic Inc., the company that has exclusive rights to salvage artifacts from the ship. According to his biography on the company's website, Nargeolet completed 35 dives to the wreck and supervised the recovery of 5,000 artifacts. He spent 22 years in the French Navy, where he rose to the rank of commander, the website says. 

British billionaire explorer Hamish Harding is on the submersible, his company Action Aviation said in a social media statement.

Harding made headlines in 2019 for being part of a flight crew that broke the world record for the fastest circumnavigation of the globe via both poles. In 2020, he became one of the first people to dive to Challenger Deep in the Pacific Ocean, widely believed to be the deepest point in the world's oceans. Last year, he paid an undisclosed sum of money for one of the seats on Blue Origin's space flight. 

The family of Shahzada Dawood and his son, Suleman Dawood, said the two are on board. A family statement said the duo had taken the "journey to visit the remnants of the Titanic in the Atlantic Ocean."

The Dawoods are a prominent Pakistani business family. Dawood Hercules Corporation, their business, is among the largest corporations in the country, with a portfolio spanning energy, petrochemicals, fertilizers, IT, food and agriculture.

OceanGate CEO and founder Stockton Rush is among the five onboard, according to a source with knowledge of the mission plan.

The company did not immediately respond to CNN's request for comment about Rush being aboard. According to the company's social media posts, he has previously piloted "Titan," the missing vessel.