This Chinese Farmer Has A Unique Hobby – He Built A Working Submarine

Lots of people have hobbies, whether it's flying a drone that's great for photography or collecting stamps. Some people also love building kit cars and all sorts of vehicles they show off every time they drive down the street. People even build boats, be they canoes or kayaks. Yet something they rarely do is build their very own submarine. That's a feat the Chinese farmer Zhang Shengwu can claim, having spent a decade constructing his own personal sub he calls Big Black Fish.

Zhang grew up along the Yangtze River in Anhui province, about 200 miles west of Shanghai, China. The area is filled with waterways and serves as an industrial center focused on steel production. Throughout his life, Zhang worked in shipping and was also a farmer, carpenter, and welder. Still, he never worked on a submarine. These vessels are typically limited to the military and research organizations that use submarines and powerful submersibles. 

It wasn't until 2014 that Zhang even saw a submarine, thanks to a television program. "I'd seen wooden and iron boats, but never one that could go underwater," he told Dawan News (via the South China Morning Post). Seeing this inspired Zhang to borrow and save enough yuan to acquire scrap steel plates, a battery, and an engine. After some months, he put together a prototype that was just under 20 feet long, weighed 2.2 tons, and could dive to a depth of around 3.3 feet. 

Zhang's prototype didn't go unnoticed, and he earned a national utility model patent for its design. Unfortunately, it had leaks while submerged, so his next project was a surface vessel that created minimal waves and received another patent. Still, he wanted a proper submarine, so he set out developing Big Black Fish. His investment cost him a surprisingly low sum of around $5,570, which all went into material and construction costs. The final design measures 22 feet long and 5.9 feet high.

Capable of diving to a depth of 26 feet, the submarine can support two occupants. As the video above shows, it works as designed. The submarine cruises at around 4.6 mph, and Zhang uses a camera affixed to a pole to inspect the riverbed before he dives. One time, Zhang even used his creation to retrieve a missing fishing net and was paid $417 for the service.

To keep the sub stable underwater, Zhang added close to two tons of concrete on the bottom of the vessel. He also has ballast tanks at both ends to aid in diving and surfacing. Each of the sub's welds is reinforced with silicone, and the instrument panel in the cockpit glows blue. Zhang uses a joystick wrapped in anti-slip rubber for steering, and Big Black Fish sails through the water with relative ease. Zhang gained viral fame online for his invention, and many have been inspired by his determination to see his dream become a reality. As he told the South China Morning Post, "People should have something to dream about."