Staff practice retrieving "Rainbow Fish," a submersible capable of diving up to 11,000 meters in the sea, on research vessel Zhang Qian in South China Sea, July 17, 2016. The vessel, named after ancient Chinese diplomat Zhang Qian (164 BC-114 BC), will test the ship's navigation abilities and equipment during its two-month voyage to the Southern Pacific. The destination is the waters near the New Britain Trench, which is more than 8,000 meters deep in the Solomon Sea near Papua New Guinea. The ship is 97 meters long and 17.8 meters wide. It has a designed displacement of around 4,800 tonnes and an endurance of 15,000 nautical miles. The ship is the first of its kind in China that is designed and built for deep-sea exploration. [Photo/Xinhua]