1) Attack submarine class 
The Delfinen was a Swedish Delfinen Class sea-going submarine of 540 tons displacement launched in 1934. The Delfinen had a top speed of 15 knots surfaced and 10 knots submerged. She carried a complement of 28 and was armed with one 4.1 inch gun; one 57 mm anti-aircraft gun; three bow 21 inch torpedo tubes and one stern 21 inch torpedo tube
Attack submarine class [Denmark]