Crowdsourcing is broadly defined as the process of obtaining information, ideas and services from a large group of people, and has become closely linked to the rapidly developing Internet and social media landscape. Crisis mapping, meanwhile, involves the collection, display and analysis of relevant data during a crisis, with varying intensity of development, from slow-burn crises to sudden-onset disasters. This tool looks at crowdsourcing as an innovative and useful approach for facilitating crisis-mapping as a whole. Benefits and potentialities as well as limits and possible strategy solutions are examined. A selection of existing tools and their target user groups are surveyed, and a cycle approach is introduced for exploring possible uses of crisis-mapping and crowdsourcing in flood management.