The IOC-FAO Intergovernmental Panel on Harmful Algal Blooms and the IOC International Ocean Data Information and Exchange Programme (IODE) in cooperation with WoRMS, ICES, PICES, IAEA and ISSHA has established and operates the IOC UNESCO Harmful Algal Information System, HAIS (https://data.hais.ioc-unesco.org/). HAIS consists of access to information on current use of taxonomic names of harmful algae, on harmful algal events, on information on biogeography of harmful algal species, an expert directory and a database on algal toxins. The HAIS data portal (http://hais.ioc-unesco.org) consists of three components i) The Harmful Algae Event Database (HAEDAT), which is a meta database containing records of harmful algal bloom events, ii) A biogeography of harmful algal species, called HABMAP within OBIS and (iii) The IOC Taxonomic Reference List of Toxic Microalgae which provides a reference list of the names and information on each species of toxic microalgae. HAIS provides the basis for the Global HAB Status Report, the first edition of which was launched 2021, https://hab.iocunesco.org/the-harmful-algal-information-system-hais/. The HAEDAT holds data relating to Harmful Algal Bloom (HAB) events that adversely impact on human society whether by high biomass (clogging of fishing nets, beach closures), aquaculture fish kills, or seafood toxin events leading to shellfish farm closures, human poisoning or even human deaths. As of March 2025, HAEDAT compromises 13012 records of HAB events. Ongoing maintenance of the database is required to address a number of challenges in ensuring that the HAEDAT continues to provide timely information on HAB events and ensures that the HAIS data portal is functional and up-to-date. These challenges include: 1. Quality assurance of data to guarantee uniform reporting standards is an ongoing major challenge. This will require updating the functionalities of the database to ensure standardization. 2. Uploading new data, and retrieving data remain challenging. To address this it is necessary to migrate HAEDAT data into a newly designed database structure that is compatible with the other HAIS components. 3. The existing application on biotoxins is incomplete and needs to be finalized to allow quicker data entry, a better search and download function than what currently exists, and finally integration into the HAIS ecosystem by regular synchronization with the World Register of Marine Species (WoRMS) and HAEDAT.