Experts have revealed for the first time the theories surrounding the notorious banging noises heard by rescuers hunting for the doomed Titan submersible.
Played for the first time in a new documentary, the sound has a regular, steady beat which caught the attention of experts - and sparked hopes that they could be SOS signals from those on board.
Coast Guard Probing Debris Field Close to Titanic Site kansascity.com - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from kansascity.com Daily Mail and Mail on Sunday newspapers.
It had been thought the banging was SOS noises by the five men. But we now know the sub was crushed as soon as it encountered trouble - so what was the banging. MailOnline investigates.