The mission is challenging, with no communication from the Titan sub and poor visibility once below the water’s surface. The search area, spanning an enormous 7,600 square miles (19,683 square km) – larger than the US state of Connecticut, has been scoured thus far.

Despite adverse weather conditions, improvements on Tuesday have allowed for increased search operations.

The extensive search operation involves cooperation among US and Canadian agencies, navies, and commercial deep-sea firms, all coordinated from Boston, Massachusetts. Military planes, submarines, and sonar buoys are being used.

On the last day of the oxygen supply hope hangs in the balance. And the search continues to be driven by the possibility of rescuing the crew alive.