Although biodiversity of marine remains high, it increasingly suffers from human interference and destruction. The world’s largest open, online, georeferenced database is the Ocean Biogeographic Information System (OBIS); it has information on a total of 120,000 species with 37 million records. The World Register of Marine Species (WoRMS) has collected taxonomic information on 220,000 global marine species. Besides these two large databases, three single-taxa databases were established for marine organisms—FishBase, AlgaeBase, and Hexacorallians of the World. Many databases on organisms are cross-taxa and include both terrestrial and marine species, such as Encyclopedia of Life (EOL), CoL (Species 2000) , Integrated Taxonomic Information System (ITIS), Wikispecies, ETI Bioinformatics, Barcode of Life (BOL), GenBank, Biodiversity Heritage Library (BHL), SeaLifeBase, Marine Species Identification Portal, and FAO Fisheries and Aquaculture Fact Sheets. Above databases were mainly established to focus on taxonomy and species descriptions. The Global Biodiversity Information Facility (GBIF), Discover Life, AquaMaps, etc. can provide integrated ecological distribution data, user customized maps, and data for download. By changing the values of environmental factors such as water temperature and salinity in an established distribution model, the distribution of a species can be predicted with different parameters. Websites of other organizations, such as Google Earth Ocean, National Geographic, and NGOs such as ReefBase, aim to raise public awareness on ocean conservation with rich and diversified content. Google Images and Google Scholar are very useful in cooperating with keywords provided by marine biodiversity websites to complement the lack of images or references. Most of the above websites are linked to each other, and thus users can access and query data conveniently. To be useful for conservation, biodiversity databases need both to promote public usage in addition to the integration and sharing of data. In this article, we build on a speech by Rainer Froese in Paris to demonstrate how to use marine biodiversity data to conduct research on the impact of climate change on fish distribution. Finally, we also briefly introduce the status of marine biodiversity databases in Mainland China and Taiwan, including the Cross-Strait collaboration, as well as recommendations for how to link to global databases.