In fragile states, recurrent transport disasters are frequently treated as isolated humanitarian incidents, despite being rooted in deeper structural and governance-related vulnerabilities. This article introduces the River Transport Vulnerability Index (RTVI), a conceptual framework designed to assess systemic disaster risk in inland waterway transport systems. The framework is empirically applied to the 2025 sequence of shipwrecks in Équateur Province, Democratic Republic of Congo. The study is based on field research conducted between March 2023 and September 2025, combining 47 semi-structured interviews, incident reconstruction, participant observation, and multisource casualty data triangulation. Five vulnerability domains are integrated into a weighted composite index: governance capacity, economic resilience, territorial control, social cohesion, and information environment. Domain weights are derived using the Analytic Hierarchy Process (AHP) based on a 12-member expert panel, allowing for structured comparison and consistency testing. The results indicate that the Équateur river corridor exhibits high systemic vulnerability, with an RTVI score of 61.6, a classification that remains stable across multiple sensitivity analysis scenarios. Vulnerability is driven primarily by regulatory non-enforcement, chronic vessel overcrowding, territorial fragmentation, and weak crisis communication mechanisms. These findings highlight the necessity of treating river transport safety as a central component of disaster risk governance in fragile state contexts.