Despite the name Battle of Cape Matapan, the actual fighting was not on Cape Matapan but out to sea in several locations.
The order of battle of the Regia Marina on 10 June, 1940.
One aspect of the Italian submarine that was commendable was their advanced Torpedo design. Prof. Carlos Calosi was the inventor of the magnetically activated torpedo, which could sink a ship merely by passing underneath its hull. That may be one of the reasons why Italian submarines had such a good attack/kill ratio.