Ocean biodiversity informatics (OBI) is the use of computer technologies to manage marine biodiversity information, including data capture, storage, search, retrieval, visualisation, mapping, modelling, analysis and publication. The latest information systems are open-access, making data and/or information publicly available over the Internet. This ranges from primary data on species occurrences, such as in the Ocean Biogeographic Information System (OBIS), to species information pages and identification guides. Using standard data schema and exchange protocols, online systems can become interoperable and, thus, integrate data from different sources. However, insufficient metadata standards, i.e. the terminology to describe data, are available for biology and ecology. Quality assurance needs at least the same rigour as for printed publications, including expert oversight (e.g. Editorial Board), quality-control procedures and peer review. An index of data use is proposed to parallel citation indices for printed journals. Other challenges include data archiving and Internet access in developing countries. Although taxon names are the central, and most unique, element of biodiversity informatics, only about one-third of the names of described marine species are currently available online in authoritative master lists. The scientific community can form alliances that build and maintain biodiversity informatics infrastructures and that address data ownership and commercialisation potential. OBI enables greater access to more data and information faster than ever before, and complements the traditional disciplines of taxonomy, ecology and biogeography. It is urgently needed to help address the global crises in biodiversity loss (including fisheries), climate change and altered marine ecosystems. For OBI to succeed, governments, science-based organisations, scientists and publishers need to insist on online data publication in standard formats that enable interoperability. This change in marine biology culture is already underway.