The
Royal Navy's
T class (or
Triton class) of diesel-electric
submarines was designed in the 1930s to replace the
O,
P, and
R classes. Fifty-three members of the class were built just before and during the
Second World War, where they played a major role in the Royal Navy's submarine operations. Four boats in service with the
Royal Netherlands Navy were known as the
Zwaardvisch class.