The Mobile Land Mine (originally named Beetle) was a British World War 2 remote controlled tracked explosive device. It was wire guided and powered by two electric motors.
The Mobile Land Mine was designed by Metropolitan-Vickers 1940. Among other trials a Mobile Land Mine was waterproofed and equipped with floats allowing it to be used against landing craft.
The design was not a success and only 50 were built.
References
Mobile Land Mine Wikipedia(Text) CC BY-SA