(The first Italian submarine can be considered the Delfino which, set up in the arsenal of La Spezia in 1890, was only completed in 1896 for a whole series of changes that were made to the original project during construction. 23,3 meters long the Delfino displaced 98 tons in emergence. The propulsion was provided by an electric motor with a power of 65 horsepower. Between 1902 and 1904 it underwent radical modernization works which also involved the embarkation of a petrol engine for navigation on the surface and a torpedo tube at the stern. The Delfino was essentially an experimental unit, even if it carried out 44 ambush missions during the First World War to defend the Venetian coast, and was among the first submarines to embark a gyroscopic compass and the periscope.)
Source: Military Navy