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.