http://www.foxnews.com/world/2017/11/28/crew-in-missing-argentina-submarine-reported-fire-leak-in-final-message.html

On November 15th a submarine from the Argentine naval forces the “ARA San Juan” with 44 crew members onboard went missing and the search began. Since the submarine was lost there has been limited communication with the vessel but in the few messages received the vessel’s captain told the naval command that water entered the submarine through the snorkel and made its way to the submarines battery by way of the ventilation system causing an onboard fire or smoke without fire. The fire was resolved and the damaged battery was isolated  and the vessel made it continued to move underwater on a secondary battery.

the vessel was commissioned 1985 and most recently refitted 3 years ago

shortly after last communication an explosion was detected in the search area while attempting to find and rescue the vessel, no debris or physical evidence has been discovered but the same unfortunate situation holds true for the location of the submarine.