Zhang Shengwu, a 60-year-old farmer from Maanshan, Anhui province, successfully built a submarine by himself, which has drawn widespread attention. The 5-metric-ton home-built submarine, named "Big Black Fish", can dive to 8 meters, CCTV News reported.

Zhang is a villager from Zhangdu village in Maanshan, Anhui province. He has been fascinated by invention since childhood. Over the years, Zhang has worked in carpentry, welding, and the shipping industry. Over 20 years ago, he returned to his hometown and built a wharf to sell sand, where he spent his days watching cargo ships come and go.

In 2014, Zhang saw a person build a submarine through a TV program, this inspired him to build one by himself. Despite his family's concerns over the cost and risk, Zhang insisted on building his own submarine.

READ MORE: Xi stresses efforts to build up submarine fleet capabilities

Drawing on his practical experience with boats and handcrafting, Zhang spent about 5,000 yuan ($700) on materials. It took him six months to build his first submarine, which is 6 meters long, 1.2 meters high and weighs 2 tons. Although his first submarine suffered from sealing issues during submersion, the invention earned him a utility model patent.

This submarine earned Zhang a national utility model patent. The only fly in the ointment is that it leaks when submerged.

In 2016, he developed a surface vessel that generated minimal waves while in motion. This invention also received a utility model patent.

However, this grassroots inventor had a bigger dream, his most ambitious project is the current new generation submarine. He invested over 40,000 yuan ($5,570) into its construction. This new submarine has a length of 7 meters, a height of 1.8 meters, and weighs 5 tons. It can dive to 8 meters, holds a capacity for two people and travels at a minimum speed of 4 nautical miles per hour.

To improve its stability, Zhang poured about 2 tons of concrete into the bottom of the submarine and added two ballast tanks at both ends. "There are two ballast tanks, water fills the tanks to dive, and drains to the surface. The concrete provides weight to maintain stability," he explained. He also reinforced all weld points and used silicone and adhesive for watertight sealing.

READ MORE: China 'welcomes' global undersea cables in its waters

Watching his submarines grow larger and his techniques improve, he dreams of building an even larger, fully functional one. "Only when you try and succeed, you do realize what you're truly capable of," Zhang said.