This dissertation examines how public institutions tasked with advancing sustainable tourism have adapted to the contradiction between sustainability commitments and growth imperatives. It argues that this contradiction is not simply a failure of governance but increasingly one of its organising conditions. Institutional arrangements developed in earlier periods now function effectively for accommodating tourism growth and maintaining public legitimacy, but poorly for reducing the sector's environmental impact.  The study develops the concept of structured unsustainability to describe this condition, alongside the related concepts of platformisation, re-entrenchment, and futurewashing. Drawing on new institutional theory, organisational and temporal governance literature, and critical policy analysis, it examines Finnish protected area governance through expert interviews and policy document analysis. The analysis also extends to European, Nordic, and Finnish Lapland tourism strategies. The work integrates spatial, institutional, and temporal dimensions of governance, and contributes to research on tourism governance, institutional inertia, and the politics of time in environmental policy.