China's new unmanned submersible, Qianlong 3, completed its maiden dive in the South China Sea on Friday. Its advantages over its predecessors－superior maneuverability and longer working time－will allow more complex studies of seabed environments for scientific or mining purposes, engineers said.

The first dive lasted around nine hours and reached a depth of about 3,900 meters in the afternoon, Liu Jian, the vehicle's chief designer, told Xinhua News Agency on Friday. The submersible is capable of reaching a depth of 4,500 meters.

The Friday test was one of two sea trials planned for the new submersible to evaluate its overall performance and its ability to collect data in resource-rich regions of the ocean, he said, adding that the tests will further strengthen China's technological capabilities in deep-sea research and development.

Qianlong 3, or "diving dragon", actually looks a bit like a clownfish, down to its signature orange and white stripes, big eyes and wavy tail. But the submersible is 3.5 meters long, 1.5 meters high and weighs 1.5 metric tons.

"All of the bionic features actually serve a purpose in improving the submersible's overall performance in complex deep-sea environments," Xu Yijun, the craft's deputy chief designer, told Xinhua.

"These designs improve stability and reliability, allowing more effective steering and better surface self-piloting capabilities," he said.

Scientists can easily spot and retrieve Qianlong 3 thanks to its bright stripes. Its big mouth holds a highly sensitive sonar system that can detect obstacles and steer accordingly, Xu said.

The two big eyes are propellers that help turn the submersible more quickly, and the fins are fully rotatable rudders that allow Qianlong 3 to move freely.

Its tail serves both as a navigation tool and a sensitive magnetic and metal detector that can notice changes in the mineral content of water. This will be useful in collecting data for deep-sea mining and scientific research, Xu said.

Unlike its predecessor, Qianlong 2－which has some similar design features and made its maiden dive in 2014－the new submersible is quieter, uses less energy and has more domestically made components, Xu said. As a result, the new vehicle can collect clearer data with less interference.

Qianlong 2 can operate for 30 hours submerged, but the upgraded submersible will have significantly longer working time, Xu said. The Qianlong series of underwater vehicles was developed by the Chinese Academy of Sciences' Shenyang Institute of Automation.