Rescuers on Wednesday rushed more ships and vessels to the area where a submersible disappeared on its way to the Titanic wreckage site, hoping underwater sounds they detected for a second straight day might help narrow their search in an increasingly urgent mission.

The full scope of the search was twice the size of Connecticut in waters 2 1/2 miles deep, said Captain Jamie Frederick of the First Coast Guard District, who noted that authorities are still holding out hope of saving the five passengers onboard the Titan.