The hunting of an unknown submarine in Patagonia: Operation Nuevo Gulf (1958)

Chronicle of an unusual hunt in Patagonian waters

This story begins in May 1958 and still remains shrouded in an aura of mystery, with many hypotheses and few certainties. It is a story that, despite the lapse of more than six decades, continues to attract attention and returns to the media from time to time for diverse reasons. I will not attempt unveiling the mystery here, because it is a puzzle in which many pieces are missing, but I will try to summarize the facts and analyze the conjectures built around it.

It all began on Wednesday, May 21st, 1958, a few kilometers northwest of Cracker Bay, in the proximity of the mouth of the Nuevo Gulf, in the province of Chubut (Argentina). Part of the Argentine fleet was in the area of the Nuevo Gulf, carrying out naval exercises. The cruisers General Belgrano, 9 de Julio and La Argentina were stationed outside the gulf, while the destroyers Buenos Aires, Entre Ríos, Misiones and Santa Cruz were sailing inside the gulf. In addition, the Ingeniero Iribas ship factory and the tugs Sanavirón and Charrúa were also part of the exercises, as well as some Navy planes.

Map of the area published by the Argentinian newspaper La Nación (May 24, 1958). Inside the Nuevo Gulf there were four destroyers (“destructores”) of the fleet, while outside there were three cruisers (“cruceros”), which did not participate in the hunt for the submarine.

The destroyers were on a naval exercise 15 miles from Puerto Madryn. One of such exercises was an eco-detection practice for sonar operator training. At 10:35 the Buenos Aires destroyer obtained an unexpected sonar contact, which minutes later was classified as a submarine performing evasive maneuvers. The situation was directly reported to the commander of the destroyer, Rear Admiral Benjamin Moritán Colman, who organized the formation of an anti-submarine hunting and attack unit (Unidad Antisubmarina de Caza y Ataque, UASCA). As a first step, the destroyer Buenos Aires launches a warning depth charge at 10:51.

As the submarine does not go to the surface, its behavior is considered to be at least illegal, so it passes to an offensive phase. The Buenos Aires and Misiones destroyers conduct coordinated attacks, and as a consequence of the explosions they lose sonar contact with the submarine. In view of this situation, the destroyers Entre Ríos and Santa Cruz join the Misiones and start a spiral search, while the destroyer Buenos Aires is located in the gulf entrance, to make a hydrophonic search of contention and prevent a possible runaway of the mysterious submarine. Minutes later, a Catalina patrol plane joins the anti-submarine search.

At 12.36 two planes from the Comandante Espora Air Force Base (Bahía Blanca) arrive to Puerto Madryn and join to the search. There is no news until half an hour later, when the Buenos Aires obtains a hydrophonic contact (latitude 42º 51.1′ S, longitude 64º 23.7′ W) on its way to the gulf entrance. From the destroyer, it switches to sonar-based ecodetection mode and maintains contact with the submarine, which remains sea-bottomed (13:50), probably as an elusive action.

At 12:36 on May 21, 1958, the submarine was heading for the exit of the Nuevo Gulf, persecuted by the four destroyers of the Argentine Navy.

At 14:10 the destroyers Misiones and Santa Cruz arrive and launch two charges of depth each. Again, as a result of the explosions, the contact is lost. The Buenos Aires and the Misiones have exhausted their ammunition, so they head for the gulf entrance, to try to prevent the escape of the submarine. Meanwhile, the Entre Rios and Santa Cruz destroyers continued the spiral search.

The weather worsened, with some showers and a little fog. At 16:40 the destroyer Buenos Aires obtains a sonar contact in the coordinates of 42º 51.3′ S latitude and 64º 27.9′ W longitude. In that place they can see the wake of the submerged submarine, which sails at low speed towards the entrance of the gulf. This could have been a tactic to avoid being detected by the hydrophone. Minutes later, the Buenos Aires loses contact again.

The Entre Rios detected the elusive submarine again with the sonar, at 17:34, about 5 miles north of Cracker bay. Together with the Misiones (so specified in the report, but I suppose it refers to the Santa Cruz, because the Misiones had exhausted its charges) they execute a coordinated attack and exhausted the depth charges. Minutes later, oil stains are seen in the water and a brief contact is obtained by sonar, that then loses.

Entre Rios destroyer. This destroyer, like the other three that participated in the hunt for the submarine, belonged to the so-called Buenos Aires Class. A total of seven destroyers was built for the Argentine Navy at the Vickers Armstrong, John Brown and Cammell Laird shipyards (United Kingdom) in 1937.

Minutes after 18:00, the Buenos Aires destroyer heads for the coast, to examine a small boat that cannot be identified from a distance because of the showers. On the way, it spots a trail to starboard (right) and a periscope appears at a distance of 650 meters. The submarine is describing a curve from west to east. The Buenos Aires prepared its artillery and tried to lunge the submarine, being assisted by the Entre Rios and Santa Cruz. The Misiones, on the other hand, examined the near-shore sighting, which proved to be a small fishing boat.

As the Buenos Aires passed over the submarine’s trail, it observed oil spots. The periscope observed was thick, light brown, and apparently there was a snorkel as well. A kind of defense was protecting the whole thing, over which a line could be distinguished, presumably with rivets. This sighting was confirmed by the officers and crew of the Artillery Command and Control stations, and also by the artillery watchers.

The Buenos Aires attack failed, and the submarine disappeared from sight. At 18:22, the same Buenos Aires destroyer gets an echo on its radar screen at 6,500 meters. This echo, from a compact object with sharp and faint contours, was evaluated as a possible submarine on the surface. Contact was lost in a few minutes.

The Buenos Aires destroyer, twin to the other destroyers that participated in the hunt for the submarine, which were part of the Buenos Aires Class destroyers. This was probably the main actor in the events of May 21 and 22, 1958, without neglecting the action of the rest of the units of the sea fleet.

The destroyer Buenos Aires, once again, detects the submarine by radar at 19:30, at about 4900 meters. The submarine moves in the direction of the coast, until it is confused with the coast, losing radar contact. At 19:55 the Buenos Aires launches three light grenades to find the target, which was close to the coast, but without positive results. The procedure is repeated at 21:27, although now the four destroyers are in formation. For the rest of the night, the four destroyers will patrol the entrance of the Nuevo Gulf.

The story did not end on May 21st, but continued the next day. At 9:20 on May 22nd, a Martin Mariner patrol plane with eight depth charges arrives and covers the area of the previous day’s attacks. At 9:23 the destroyer Misiones obtains a clear sonar contact and forms an attack unit with the Santa Cruz and the patrol plane.

The destroyer Misiones was one of the lasts to detect the submarine on the morning of 22 May 1958.

At 9:35 a four-engine Douglas DC4 aircraft, registered CTA-2, arrives to Puerto Madryn with depth charges to supply the destroyers. These were loaded onto the Sanavirón patrol, which transported them to these ships. Minutes later, two Catalina aircrafts arrive to the operation area, for exploration and attack tasks.

At 10:15, the destroyers Misiones and Santa Cruz, which were still in sonar contact with the submarine, lead the attack of the Martin Mariner aircraft, which launches depth charges in two successive passes. After this attack contact is lost and all searches by both ships and aircraft are unsuccessful.

Front page of the Argentinian newspaper La Nación of May 24, 1958. All the Argentinian newspapers included the news of the submarine on the front page.

The chase ends at 16:30 on 22 May, when the search with the ships is suspended, although an aerial surveillance of the area is maintained. There were many versions about the origin of the submarine, and even about its real existence. Some those doubted the existence of the submarine and argued that it was a campaign by the Navy to obtain funding to acquire more modern equipment, and those who claimed that the submarine was a whale. Those who claimed that the submarine was real, argued that the submarine was American, Russian, or Brazilian, although at no time was there a minimally concrete evidence of its identity.

Was the submarine real? Where did it come from?

Confusing a submarine with a whale is a questionable idea. In May it is possible to see Southern Right Whales in the Nuevo Gulf, but it is difficult to confuse a whale with a submarine (especially considering the behavior of the strange intruder, which does not resemble a whale). The possibility that it was all a hoax organized by the Navy to justify the acquisition of material cannot be discarded, especially considering these were years of the Cold War and political instability as a context. Contrary to both allegations, there were several witnesses of the submarine sighting, as well as concrete contact records from sonar. In the case of a Navy conspiracy, it is rare that after so many years none of those who participated in that operation have broken the silence (it is rare but not impossible).

If, on the other hand, the events of 21 and 22 May 1958 are accepted as true, the doubt remains as to the origin of the submarine. The newspapers of the time, as well as those who analyzed the news years later, assumed that the submarine could have three different nationalities: USA, USSR, or UK. None of the three countries assumed the submarine was theirs, although various sources tried to induce the news that it was of Soviet origin. The tabloid Daily News published on its cover “Red submarine bombed off Argentina”, while the Daily Telegraph said it was “almost certainly Russian”. But the majority of the newspapers did not take a position and only speculated on the possibilities. On 26 May, according to the Argentinian newspaper La Nación, a false version circulated in the province of Cordoba which claimed that Argentina had broken off diplomatic relations with Brazil because of the submarine incident, something which hours later was proven to be a fake.

The Chamber of Deputies of the National Congress called for a Secret Session in June 1958, where the Marine Minister presented the facts to the national deputies. The session ended at 14:07 on June 13, 1958, with a brief press release that said

The Honorable Chamber of Deputies of the Nation declares:

l) To be satisfied with the explanations of the Marine Minister about the naval action carried out by units of our Navy with a foreign submarine in Nuevo Gulf, coinciding with the report opportunely given to the country by the Argentine Government.

2) To make public a declaration that the Navy of the Republic has acted in the emergency with Argentine responsibility in defense of the Nation’s sovereignty.

Some of the pages from the transcription of the secret session of June 13, 1958. Source: Department of Archives, Publications and Museum, Parliamentary Secretariat of the Chamber of Deputies.

The deliberations of this secret session were secret for almost 50 years, until Law 26134 was enacted in 2006, which left without effect the secret or reserved character of any law that has been approved with such condition. Since then, any citizen has access to this material. A reading of the text of that session reveals a long and rather disorderly discussion, from which some interesting data can be extracted:

  • The Argentine Navy assumes the submarine is neither American nor English.
  • From the observations made on the site, it can be deduced that the submarine is of the type manufactured in the USSR, but its flag cannot be clearly stated.
  • An observation made by Congressman Silveira Marquez, from the province of Misiones, generates a confused discussion that does not conclude in anything, but in which it is suggested that an ambassador of a foreign country, not revealed, would have contacted an admiral of the Argentine Navy to inquire him for information about the place where the incident with the submarine took place.
  • The Marine Minister, when questioned by deputy Leon, from the province of Chaco, acknowledged the presence of a ship anchored in the port of Valparaiso (Chile), which would be a Soviet Navy tank, which raises some doubts about the presence of submarines of that nationality in Patagonian waters.
The news about the submarine was reported not only by the local media, but also by the most important newspapers in the world.


To this day, all that concerns to the intruder submarine in the Nuevo Gulf is still in shadows. The identity of the ship is still a mystery and no one has spoken or contributed anything new in these 62 years. The possibility that it may have been a Navy conspiracy to justify the acquisition of material cannot be discarded. In fact, the Marine Minister made it clear at the secret session in the Chamber of Deputies that the equipment used to chase the submarine was precarious. However, the truth is that many people saw the submarine. In case it was a conspiracy of the Argentine Navy, it is rare that after so many years none of those who participated in that operation broke the silence (rare, but not impossible). Nor does it seem likely that a foreign nation would admit to having violated Argentina’s sovereignty in times of peace; it would bring no benefit to anyone. Perhaps it could be expected that some of those who sailed in that submarine, or their descendants, would reveal something at any moment, but for now there is nothing. There are no references to exploratory dives in the area where the submarine was sighted, but everything suggests that unless there is a sunken submarine at the bottom of the Nuevo gulf it will be impossible to verify in situ any of the things described in the government’s report. But do not be discouraged, if none of these theories convince us, we can always use the resource of the alien submarine.

This article is available in Spanish on the blog Bahía Sin Fondo [Part 1 / Part 2]


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