The last known video of the missing Oceangate submarine beginning its dive, with one of the passengers seen waving, has been posted online.

Abbi Jackson, 22, a videographer employed on the mothership, the MV Polar Prince, shared the video as the vessel submerged beneath the waves in the Atlantic Ocean.

Miss Jackson captioned the post: ‘Watching a submarine go down to the Titanic.’

The vessel was first reported missing on Sunday, eight hours after it began its dive.

This is despite the submarine losing contact with the mothership just one hour and 45 minutes into its voyage to see the wreckage of the Titanic.

The company’s CEO Stockton Rush and British explorer Hamish Harding are on board, along with French submersible pilot Paul-Henri Nargeolet and the Pakistani businessman Shahzada Dawood, with his son Sulaiman.

Miss Jackson filmed Mr Nargeolet as part of her Tik Tok, saying he has visited the wreckage 37 times.

The 77-year-old is seen sitting on the side on an inflatable boat before waving and smiling at the camera.

Abbi Jackson is a videographer on the missing submarine’s mothership (Picture: TikTok/@abbijaxxxson)

She filmed Paul-Henri Nargeolet waving to the camera (Picture: TikTok/@abbijaxxxson)

Since posting the video, Miss Jackson thanked well-wishers for their concern and asked them to pray for the five people on board.

They only had 96 hours worth of oxygen as they made their descent four days ago, meaning the time to find them is quickly running out.

Search efforts have been ramped up in a last ditch attempt to find the five passengers, with 10 extra ships and several remotes submarines joining the search today.

The five people on board only had 96 hours of oxygen when they began the dive on Sunday (Picture: Oceangate Expeditions)

The US Coast Guard say the cut-off time to recover the undersea craft is 7.18am local time – which is 12.18pm UK time.

There was fresh hope yesterday after ‘banging’ sounds were heard underwater, giving rescue teams hope that there were potential signs of life.

Rear Admiral John Mauger of the US Coast Guard, who is leading the search said the noise ‘is a target’ for the search teams.

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‘Watching a submarine go down to the Titanic.’