According to officials who are familiar with the characteristics of the missing submarine, if submerged, there is approximately a seven day supply of oxygen. The vessel has been missing since November 15th…. President Trump tweeted about it today:

MAR DEL PLATA, Argentina/BUENOS AIRES (Reuters) – The search for an Argentine navy submarine missing in the South Atlantic for one week reached a “critical phase” on Wednesday as the 44 crew on board could be running low on oxygen, a navy spokesman said.

Dozens of planes and boats were searching for the ARA San Juan, a mission that has plunged relatives of the sailors into an anguished wait for news and transfixed the South American country of 44 million people.

If the German-built submarine, in service for more than three decades, had sunk or was otherwise unable to rise to the surface since it gave its last location on Nov. 15, it would be using up the last of its seven-day oxygen supply.

“We are in the critical phase…particularly with respect to oxygen,” navy spokesman Enrique Balbi told reporters. “There has been no contact with anything that could be the San Juan submarine.” (read more)