SM U-104[Note 1] was a German Type U 57 U-boat during the First World War.

U-104 was built at AG Weser in Bremen, launched on 3 July 1917 and commissioned on 12 August 1917.

Kurt Bernis and was responsible for the sinking of nine vessels of a total of 14,721 gross register tons (GRT).

[3] On 25 April 1918 the U-104 was engaged by USS Cushing in St. George's Channel and severely damaged.

Later the same day HMS Jessamine came upon her and dropped further depth-charges, sinking her and leaving but a single survivor of her 42-member crew.