Photo taken on Jan. 2, 2015 shows a piece of sulfide collected by China's deep sea manned submersible Jiaolong from seabed of a hydrothermal vent in the southwestern Indian Ocean. Jiaolong carried out the first dive on a mission to study active hydrothermal vent in the southwestern Indian Ocean on Jan. 2. It was the first time for the submersible to take the second batch of pilot trainees in the diving, which was intended to enable the trainees to learn some skills of submersible operation in active hydrothermal vent and collect samples of hydrothermal fluid, sulfide, rocks, sediment and water. (Xinhua/Zhang Xudong)