U-boats type XXIII belonged to the new generation of German WWII submarines. Designers paid the main attention to increase of speed and range in the submarine position. To the mid 1943 there have designed projects of “electric subs” – ocean type XXI and little coastal type XXIII. The leading submarine U 2321 has delivered June 12, 1944. To the end of the war there were assembled 63 ships. From February 1945 six submarines have performed 10 battle cruises and have sunk 4 Allied merchant ships without self-losses. After the end of war U 2353 has delivered to USSR and served in Soviet Navy as N-31 to 1953. In 1956 sunken U 2365 и U 2367 have raised and have became first FRG Navy submarines as “Hai” (“Shark”) and “Hecht” (“Pike”).