<![CDATA[This study aims to determine the state of sustainable tourism development in Toba Regency after the 2025 F1H2O Event, explain the efforts made by the Toba Regency Culture and Tourism Office and the Mulia Raja Napitupulu Foundation, and examine the supporting and inhibiting factors in the development process. The study used a descriptive qualitative method with data collection techniques including observation, in-depth interviews, and documentation. Data validity was tested through triangulation of sources, techniques, and time, and analyzed using an interactive analysis model. The results show three main findings. First, tourist visits in the first and second years of F1H2O experienced a significant increase, but in 2025, there was a decline due to inadequate preparation and the disruption of road access due to natural disasters that struck North Sumatra, which impacted Lake Toba. Nevertheless, this event brought positive changes in the form of increased human resource capacity, the creation of new jobs, and the increasing international recognition of Lake Toba. Second, post-event tourism development efforts were carried out through programs by the Department of Culture and Tourism, including cultural festivals, sporting events, digital promotions, and the opening of new tourist destinations; as well as efforts by venue management through facility improvements, human resource training, and the preservation of Toba Batak culture. Third, supporting factors included the natural beauty of Lake Toba, central government infrastructure support, international promotion, and local community involvement. Inhibiting factors included unresolved land disputes, low public tourism awareness, minimal ongoing training, suboptimal coordination between stakeholders, and limited post-event budgets.]]>
