BUENOS AIRES, Argentina (AP) — Argentina’s navy says it’s not giving up hope that crew members could be alive 11 days after a submarine vanished off the Atlantic coast with 44 people aboard.

Navy spokesman Enrique Balbi told a news conference Sunday that the passage of time doesn’t rule out “a situation of extreme survival.”

Officials say they fear there was an explosion involving the vessel that lost contact on Nov. 15. And experts say the ARA San Juan had only about 10 days of oxygen supply at the outside.

It had been expected to dock on Nov. 19 in the port of Mar del Plata.

So far there’s been no sign of the sub, but Balbi said the multinational search effort is continuing.