US Coast Guard base in Boston as search for missing submersible continues

A massive search and rescue effort for a missing submersible near the wreck of the Titanic entered a critical stage late Wednesday, with just one night left before the oxygen supply for the five people on board runs out.

US and Canadian military planes, coast guard ships, and teleguided robots are focusing their efforts in the North Atlantic close to multiple "underwater noises" detected by sonar late Tuesday and Wednesday.

The sounds raised hopes that the passengers on the small tourist craft are still alive though experts have not been able to confirm their source. The submersible, named Titan, was carrying a pilot, three wealthy adventurers and the submersible company’s CEO.