Rescuers are running against time to save the occupants of the Titanic tourist submarine that went missing in the Atlantic Ocean on Sunday. According to rescuers, the submarine has only 20 hours of oxygen left. The US Coast Guard termed the mission as very complex and difficult with people working round the clock to save the lives of five people onboard the missing submarine.<br />'' <br />''<span style="color: #222222;">Meanwhile, the rescuers recorded a noise potentially being generated by the occupants of the sub and as a result, they relocated remote-operated vehicles (ROVs) on sight. Underwater operations have been relocated to investigate the noises, the US Coast Guard has said, but so far they have not found anything.</span><br />