waterwaymap.org
WaterwayMap.org is a website that visualizes river basins and waterway networks derived from OpenStreetMap data. It renders interactive maps showing how rivers, streams, and other watercourses are connected across regions worldwide, helping users explore hydrological connectivity and drainage patterns. The tool detects and highlights loops in waterways, identifies mapping issues, and supports community efforts to improve waterway tagging in OpenStreetMap. It has been presented at State of the Map Europe conferences and FOSSGIS, and is used by mappers who contribute river and stream data to OpenStreetMap. The site serves OpenStreetMap contributors, hydrologists, cartographers, and anyone interested in understanding global river basin topology and waterway mapping accuracy.