The Motorised Submersible Canoe (MSC) was a secret underwater vehicle designed for the SOE. It had the capability to dive underwater for stealth missions. It was nicknamed Sleeping Beauty when its creator Major Hugh Reeves was seen sleeping in one.

While clever in design, it never gained fame due to the secrecy and lack of successful operational use during WW2. However, it did influence future developments in underwater warfare.

Two replicas are on display today.

The U.S. spy museum in Washington D.C.
Western Australian Maritime Museum, in Perth Australia

More information can be found on this topic:
https://en.wikipedia.org/wiki/Motoris...