The deep-diving submersible vehicle that was lost in the North Atlantic on Sunday was believed to have less than two days of oxygen remaining on board as of Tuesday night, as ships and aircraft raced to search an area larger than Connecticut.

The submersible, the Titan, had five passengers on board — its maximum capacity — and it was a tight squeeze. Promotional materials showed an interior with no seats, only a flat floor passengers could sit on, and a single view port 21 inches in diameter.