The Japanese Type 95 Ha-Go

Hunter1911, on 03 December 2013 - 03:57 PM, said: Ka-Tsu is also an interesting concept for those interested.

It had an unique feature: portions of the vehicle were completely sealed off so it could be carried submerged on the deck of a submarine.
In the late stages of the war some modified versions could even carry torpedoes. Although their effectiveness in this role would be slight to say so.

The Japanese actually planned on using them to assault docked US ships in areas where ships or subs could not travel.
They planned on dropping them of from a sub near the enemy target and letting the Ka-Tsu use their own propulsion to reach the target and fire the torpedo's at it.