The study assesses global river connectivity to map the world's remaining free-flowing rivers. It defines free-flowing rivers as those with natural aquatic ecosystem functions and services largely unaffected by changes to fluvial connectivity, allowing unobstructed exchange of material, species, and energy. The research identifies five main pressure factors affecting river connectivity: river fragmentation, flow regulation, water consumption, road construction, and urbanization. Using a high-resolution river network model, the authors calculate a Connectivity Status Index (CSI) for each river reach, ranging from 0% to 100%. Rivers with a CSI above 95% over their entire length are classified as free-flowing. The results show that very long rivers (>1,000 km) are the most threatened, with only 36% remaining free-flowing and 23% connected to the ocean. The study emphasizes the urgent need for global and national strategies to maintain and restore free-flowing rivers, highlighting the critical role of these rivers in sustaining ecosystem services and biodiversity.The study assesses global river connectivity to map the world's remaining free-flowing rivers. It defines free-flowing rivers as those with natural aquatic ecosystem functions and services largely unaffected by changes to fluvial connectivity, allowing unobstructed exchange of material, species, and energy. The research identifies five main pressure factors affecting river connectivity: river fragmentation, flow regulation, water consumption, road construction, and urbanization. Using a high-resolution river network model, the authors calculate a Connectivity Status Index (CSI) for each river reach, ranging from 0% to 100%. Rivers with a CSI above 95% over their entire length are classified as free-flowing. The results show that very long rivers (>1,000 km) are the most threatened, with only 36% remaining free-flowing and 23% connected to the ocean. The study emphasizes the urgent need for global and national strategies to maintain and restore free-flowing rivers, highlighting the critical role of these rivers in sustaining ecosystem services and biodiversity.