The World-wide Hydrogeological Mapping and Assessment Programme (WHYMAP) provides data and information about the Earth´s major groundwater resources. The programme compiles hydrogeological information from regional, national and global sources, and visualizes the groundwater data as printed maps, web map application and web map service. These products provide information on quantity, quality and vulnerability of the groundwater resources on Earth and help communicating groundwater related issues to water experts, decision makers and the general public.