Launched in 1933, the Smeraldo – a Sirena class submarine of the Royal Navy, which secretly participated in the Spanish war – disappeared in the Sicilian Channel in 1941 with 45 crew members on board. A sonar search off Tabarka may have reopened the case of her disappearance.
Among the wrecks of submarine cemetery discovered off the coast of Tunisia there could also be the Emerald submarinean Italian Royal Navy vessel that vanished into thin air during the Second World War.
The Smeraldo, a Sirena class submarine launched in Taranto in 1933, sank in September 1941 with 45 men on boardfor reasons still unknown. During that last mission it was supposed to attack a British convoy, but never returned to base. Yet, Royal Navy records do not report any sinking of an Italian submarine in that period, which is why historians believe the submarine disappeared due to a mine.
How the Emerald of the Royal Navy was made
The Emerald belonged to the class “600” (Siren class, specifically) and almost 60 examples of this type were built. They were in fact an important underwater component for the Royal Navy in the Mediterranean Sea. It should be specified that this was a coastal submarine, therefore conceived for quick ambushes and maneuvers in the Mediterranean basin, but not for long ocean cruises.
It was just over long 60 meters and less than 6 and a half meters wide, and used two Tosi diesel engines which allowed him to reach a maximum speed of 14 knots (about 26 km per hour). Underwater, however, he used two Magneti Marelli electric motors with around 800 total horsepower, which pushed it up to 7.5 knots (around 14 km per hour).
His strength was in his 6 x 533 mm torpedo tubes (4 at the bow and 2 at the stern), supported by a reserve of torpedoes on board. But not only that: the Emerald also had on the main deck a 100/47 mm cannon and of twin 13.2 mm machine guns for air defense.
The 45 men on board certainly did not lead an easy life, given that they had to share narrow spaces, with the air spoiled by combustion fumes. But however inconvenient it was, it was an essential means for Italian military history: in fact, it was precisely from the Emerald that the first torpedo launched by an Italian submarine of the Second World War was launched.
The history of the submarine and the last mission: the bottleneck of the Sicilian Channel
After the launch in 1933 and the training period, the Smeraldo was stationed in Taranto and, from 1935, passed to the submarine squadrons based in Messina.
Even before the Second World War, however, took part clandestinely in the Spanish civil warwith a single mission between 25 August and 6 September 1937 in the waters of Cape Palos (southeast coast of Spain) which ended without results.
When Italy entered the war on June 10, 1940, the Emerald was located at Tobrukin Libya, and set sail on his first mission: on the night of 11 June he was the first Italian submarine to launch a torpedo in the conflict, even if the shot missed due to the rough sea.
A few weeks later he was located by some British destroyersand that’s when he survived one of the toughest hunts ever suffered by an Italian submarine: he was hit by approx 200 depth chargessuffering serious damage. Yet, it didn’t sink.
The attack forced the submarine to continue at a deep altitude and at minimum speed, however escape the Allies’ sonars. Finally, it resurfaced and, despite serious damage, continued towards Tobruk.
Once it reached the Libyan base, the damage to the hull and equipment soon proved to be too extensive for the local shipyards, and so the Emerald was transferred to Sicily, to the Augusta Arsenal, where it would spend the next five months carrying out all the repairs necessary.
Once recovered, he returned to sea for other missions betweenEgypt, Malta And Creteall without results.
Finally, the Emerald cast off the city of Augusta for its sixteenth (and, unfortunately, last) mission on September 15, 1941. The destination? The sea along the Tunisian coast (west of Malta), where he would have laid an ambush for convoys British.
The Channel of Sicily it was then a very dangerous place to cross, given that it was guarded by the Allied anti-submarine fighters and dotted with extensive mine barrages.
To escape enemy radio direction finding, rigorous radio silence: the Italian Supermarina, therefore, did not receive any signal, however do not betray the position.
On September 26, however, the submarine was supposed to return, and did not reappear at the base. It was then clear that something had happened, and the Emerald was declared officially missing at sea, and with him the commander Bartolomeo La Penna and the entire crew of sailors.
How it could have sunk and the alleged discovery after 80 years in Tunisia
Having no source nor an SOS to refer to, the end of the Emerald was reconstructed through the hypothesis of naval historians comparing theoretical routes ei war bulletins of that era.
According to the most accredited hypothesis, the submarine would have impacted with a naval mine. The waters through which he had passed, in fact, were dotted with defensive mine barriers laid by the British and French. It didn’t take much to blow up: if the submersible hit a mine moored under the water, in fact, the shock wave would tear it apart instantly, and flooding was a matter of a matter of seconds.
In 2018 the Belgian diver Jean-Pierre Missonwhich has been conducting explorations of the southern Mediterranean seabed for years using sonar and acoustic systems, announced on discovery of a series of military submarine wrecks about 70-90 meters deep offshore Tabarka.
On 1 November 2026, a TG1 report returned to this very story: among the carcasses, in fact, there was also that of the Emerald, together with eight British submarines. The identification, however, is not yet confirmed, and a further investigation will be needed.direct inspection of the wrecks to know for sure if the unforgotten submarine is among the wrecks.
