Argo was the lead ship of her class of two submarines ordered by the Portuguese government, but taken over and completed for the (Royal Italian Navy) during the 1930s.
The Argo-class submarines displaced surfaced and submerged. The submarines were long, had a beam of and a draft of . They had an operational diving depth of . Their crew numbered 46 officers and enlisted men.
For surface running, the boats were powered by two diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a electric motor. They could reach on the surface and underwater. On the surface, the Argo class had a range of at ; submerged, they had a range of at .
The boats were armed with six internal torpedo tubes, four in the bow and two in the stern for which they carried a total of 10 torpedoes. They were also armed with a single deck gun, forward of the conning tower, for combat on the surface. The light anti-aircraft armament consisted of four single machine guns.
Argo was built by Cantieri Riuniti dell'Adriatico in its Monfalcone shipyard. The submarine had initially been ordered in 1931, but was acquired by the Italians when Portugal cancelled the order. She was launched in 1936, and saw action in the Second World War.
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