A research team take a group photo on Chinese deep-sea explorer ship Zhang Jian as it sails in waters near the equator at the Pacific Ocean, Aug. 2, 2016. The ship sailed across the equator into the southern hemisphere on Tuesday. [Zhang Jiansong / Xinhua]

A fire drill is conducted on Chinese deep-sea explorer ship Zhang Jian, Aug. 2, 2016. [Zhang Jiansong / Xinhua]

A research team take a group photo on Chinese deep-sea explorer ship Zhang Jian, Aug. 2, 2016. [Zhang Jiansong / Xinhua]

Chinese deep-sea explorer ship Zhang Jian sails in waters near the equator at the Pacific Ocean, Aug. 2, 2016. [Zhang Jiansong / Xinhua]

A rainbow is seen ahead Chinese deep-sea explorer ship Zhang Jian, Aug. 1, 2016. [Zhang Jiansong / Xinhua]