A torpedo which is designed to be steered to its target
by a human operator riding inside or astride it. Some of
them could travel submerged to a depth of tens to a few
hundred feet, while others were strictly surface craft
(think a jet ski that you ride while prone).
They were used by both Germany and Japan during World War II.
For neither nation were they particularly effective.
The Japanese Kaitens were not initially intended as
instruments of a suicide attack, though late in the war they
became such, to the point that later models did not have the
escape hatch for the operator that the earlier ones had.
Only two Allied ships were sunk by them, while eight Japanese
host submarines were lost.
I do not know if the term kamikaze included the torpedo pilots
of the last days of the war. Since the Japanese apparently don't
use that word even for the airplane pilots, I suppose it doesn't.
The German contribution to the art went through several
generations late in the war. They were not intended as
suicide weapons either, though the fatality rate for the
operators was quite high, even when no engagement with the
enemy occurred. Many of the operators died from exhaustion,
or carbon dioxide poisoning as a result of failure of their
breathing apparatus. Often, the separate torpedo would not
detach from the cockpit and would carry the pilot to
The first German use of their Neger was intended to
help celebrate the Führer's
birthday in 1944. Due to logistical and other problems, a force
of thirty did not manage to engage a single ship. In July, their second
try sank three Allied minesweepers and a few small ships, in exchange
for nine of the Negers; later that month,
a force of twenty permanently disabled the Dragon, a
losing 16 of their own, and the British destroyer Isis.
They were then not used for the rest of the war.
Italy, on the other hand, was the first to develop a human torpedo
(in 1935) and had good success with them during the war, sinking
two British battleships and a cruiser (HMSs Queen Elizabeth,
Valiant, and York), and 25 other
naval or merchant ships.