Overexploitation of ocean resources is a pressing global environmental issue, with over one-third of fish stocks depleted and unsustainable practices increasing over the last decades. Despite regulations, inadequate surveillance and data opacity impede effective ocean governance, fuelling illegal fishing, which accounted for over 20% of the global catch in 2020 (Widjaja et al., 2023). Stakeholders propose various countermeasures, but their efficacy is hindered by the lack of surveillance technology and accessible data. Global Fishing Watch (GFW), a US-based NGO, addresses this need by enhancing fishing data accessibility worldwide. The GFW platform integrates multiple data sources to provide open access to industrial fishing vessels’ movement and activities, enabling stakeholders to contribute to fish stock preservation. However, there is a gap in understanding GFW's socio-technical trajectory. This thesis analyses GFW's evolution within the context of system innovations and sets out to understand to what extent the theoretical characteristics of (sustainable) system innovations are reflected in the emergence of the GFW platform. This is relevant because system innovations will be essential to achieving the Sustainable Development Goals issued by the United Nations. However, the related research body lacks case studies that help understand sustainable system innovation, especially in the primary sector. This thesis follows the framework of biographies of artefacts and practices and relies on semi-structured interviews with key actors and publicly available documents. The analysis of the interviews and literature reveals that the GFW platform fulfils many of the criteria of being a system innovation according to the multi-level perspective (Geels, 2004) and the recent add-on by Leadbeater and Winhall (2020). However, it deviates from the established theory several times. In addition, the platform faces potential challenges, such as the limited diffusion potential and an unclear future funding strategy, which might hinder the platform’s diffusion. Despite the deviations, the GFW platform exemplifies sustainable system innovation in ocean surveillance to combat illegal fishing activities.