Haiyi (sea wings”) is made from carbon fiber and was built at CAS Shenyang Institute of Automation. It can monitor sea water temperature, salinity, turbidity, chlorophyll and oxygen content. Haiyi does not have a propeller. In its body, there is an oil bag that works like a fish bladder, and a moveable battery.The depth was reached in the Mariana Trench and monitored by the mother ship Tansuo-1. In Oct 2014, Haiyi swam 1,022.5 kilometers nonstop in 30 days during a test.”

CAS news release, March 24, 2017