According to Guinness World Records, the smallest submarine ever made is just 4mm, or 0.157 inches long, and was created in 1999 by the German company MicroTEC as a mini medical device.

Big surprise, right? That’s precisely how [Peter Sripol] approached his latest project, which he’s claiming is the world’s smallest remote control submarine. We’re not qualified to say if ...

"Presumably, the discovered diesel submarine is the submarine 'M-49' of the Pacific Fleet, communication with which was lost ...