Italian submarine Alagi was an Adua-class submarine built in the 1930s serving in the Regia Marina during World War II. She was named after the Amba Alagi mountain in Ethiopia, which was at the time part of Italian East Africa

The Adua-class submarine was the fourth sub-class of the 600 Series of coastal submarines built for the Regia Marina during the 1930s. There were 17 submarines in this class, almost all named after places in Ethiopia which had been an Occupied by Italy since 1936, but only one, Alagi, survived World War II. Three submarines of this class were sold to Brazil before the war and replaced with submarines of the same names.