Disappearance of ARA San Juan

On 15 November 2017, the Argentine Navy submarine ARA San Juan (S-42) lost contact with command while transiting from Ushuaia to its home base at Mar del Plata following a naval exercise in Tierra del Fuego. The vessel, a TR-1700-class diesel-electric submarine built in West Germany and in Argentine service since 1985, had at least 44 servicemen aboard, including Eliana Krawczyk, Argentina's first female submarine officer. The submarine's last reported position was approximately 200 nautical miles southeast of the San Jorge Gulf, and it carried oxygen sufficient for no more than seven days while submerged.

A large-scale international search and rescue operation began on 17 November 2017, eventually involving more than 4,000 personnel, 27 ships, and 30 aircraft from 13 countries, including Argentina, the United States, the United Kingdom, Brazil, and Chile, scouring roughly 500,000 square kilometres of ocean. During the search, several potential leads were investigated and later ruled out, including reported satellite phone communications, sonar-detected "banging" sounds later attributed to a biological source, a heat signature detected by a U.S. Navy aircraft, and flares sighted by a British ship. On 23 November 2017, the Argentine Navy reported that international seismic monitoring posts had detected an event consistent with an explosion on 15 November, near the submarine's last known position.

On 27 November 2017, an Argentine Navy spokesman disclosed that the submarine's final report indicated a snorkel had leaked water into its forward battery compartment the day before contact was lost, causing a fire that was extinguished before the crew disconnected the forward batteries and continued on the aft batteries alone. On 30 November 2017, after 15 days, the Navy declared the rescue phase over and shifted the operation to a search for the wreck, effectively acknowledging no survivors were expected among the 44 crew. The loss was described as the worst submarine disaster since the 2003 accident involving Chinese submarine 361, and the second-worst peacetime naval disaster in Argentine history after the 1949 sinking of the minesweeper ARA Fournier.

International search assistance largely ended by early 2018, and in February 2018 the Argentine government offered a reward of approximately USD 5 million for information leading to the submarine's location. Starting 7 September 2018, the U.S.-based seabed survey company Ocean Infinity conducted a renewed search under a no-find, no-fee arrangement. On 16 November 2018 — a year and a day after the disappearance — Ocean Infinity located the wreck at a depth of 907 metres, roughly 20 kilometres from the previously reported seismic anomaly. Photographs released by the Argentine Navy showed the vessel's pressure hull imploded and broken into several pieces scattered across an 8,000-square-metre area of seafloor. Ocean Infinity received a US$7.5 million reward for the discovery.

In the aftermath, Argentina's defence minister dismissed the Navy's Chief of the General Staff in December 2017. Documents later provided to the judge investigating the incident, reported by Infobae in February 2018, indicated the submarine's mission had included surveillance of British civil and military vessels near the Falkland Islands. A monument commemorating the 44 crew members was unveiled at the Mar del Plata Naval Base on 24 October 2021.