There have been Four B classes of submarine:
The British B class of eleven submarines launched in 1904–1906
The Norwegian B class of six submarines built from 1922 to 1929
The Spanish B class of six submarines launched in 1922-1925
The United States B class of three submarines launched in 1907
The Danish B-class of five submarines launched between 1915-1916
The Japanese Type B submarine, three classes submarines
I-15-class submarine (Type B1 submarine)
I-40-class submarine (Type B2 submarine)
I-54-class submarine (Type B3 submarine)
