To foster knowledge and ideas exchange within the marine environmental science community and, in particular, to promote interdisciplinary studies, the State Key Laboratory of Marine Environmental Science (MEL, http://mel.xmu.edu.cn/en) of Xiamen University initiated the Xiamen Symposium on Marine Environmental Sciences (XMAS), with the overarching theme of The Changing Ocean Environment: From a Multidisciplinary Perspective. The XMAS-III (http://mel.xmu.edu.cn/conference/3xmas/) was held in Jan 2017, attracting over 620 participants from more than 140 institutions across 21 countries.