1942(Helge Fischer WI-4b)
- Class: Adua - 17 submarines of 1936-37
- Displacement: 680 (surface)/850 (submerged) tons
- Dimensions: 197 x 21 x 15.5 ft.
- Machinery: 2-shaft Diesels, H.P. 1,200/800 = 14/7.5 knots
- Armament: 6-21 in. T.T.; 3 human torpedoes
- Complement: 45
- Builder: Odero-Terni-Orlando, Muggiano
- Keel Laid: 30 Jan 1937
- Launched: 6 Jan 1938
- Completed: 25 Mar 1938
- Notes: Specially modified to carry 'human torpedoes', Scire launched three two-man teams outside Alexandria harbor on the evening of 18 Dec 1941. They successfully penetrated the net defenses and placed their charges under the battleships HMS Queen Elizabeth and HMS Valiant, and the large Norwegian tanker Sagona. The charges exploded the next morning, 19 Dec, sinking both battleships onto the shallow harbor bottom. The tanker and destroyer HMS Jervis, which was moored alongside for refueling, were also badly damaged. Both battleships were raised and repaired eventually, but they were out of action for more than one year each.