With a submarine crewed by 44 sailors still missing off the coast of Argentina, we recall 10 of the worst submarine disasters in history, all from the last few decades.
The Argentine ARA San Juan submarine, with 44 crew on board, disappeared 430km (270 miles) off the Argentine coast last Wednesday after reporting a mechanical breakdown.
The US Navy’s Undersea Rescue Command hopes to deploy a Pressurized Rescue Module (PRM) in an attempt to rescue the crew members.
The PRM is operated remotely by a crew on a ship. It can descend to 610 metres (2,000 feet) and can carry up to 18 people, including two attendants.
A vital feature of the PRM is its transfer skirt – used to connect the module to the submarine – which can rotate to a 45-degree angle. The PRM can remain upright even if the sub is resting at an angle, which eases the rescue process.
The US Navy sent a ship with special tracking equipment and deep-sea rescue equipment to join the search. Chile and the UK sent aircraft to search the area.