A mapathon is a learning event where volunteers meet to focus mapping efforts on the same region. To organize one, choose a task from the HOT Tasking Manager, register the event, find a venue, and spread the word. Mapathons organized by Politecnico di Milano included traditional mapping parties, emergencies mapping, and ones with children. Validation is important, especially for children, to avoid common mistakes. Successful mapathons thank participants and quantify results.