Resumen: Tourism is often seen as the ‘golden ticket’ for the development of many islands. The current COVID-19 pandemic, however, has ground global tourism to a halt. In particular, islands that depend heavily on tourist inflows—including mass-tourism islands, and small island developing states (SIDS)—have seen their revenues diminish significantly, and poverty rates increasing. Some alternative-tourism islands have fared better, as they have focused on providing personalized, nature-based experiences to mostly domestic tourists. This article focuses on the experiences of mass-tourism islands, SIDS, and alternative-tourism islands during the COVID-19 pandemic, and offers possible post-pandemic scenarios, as well as recommendations for sustainable island tourism development. Although the pandemic has largely had a negative impact on the tourism sector, this is a unique opportunity for many islands to review the paradigm of tourism development. In this newly emerging world, and under a still very uncertain future scenario, the quadriptych of sustainability is more important than ever. Responsible governance and management of islands’ natural resources and their tourism activities, addressing climate change impacts, the diversification of islands’ economies, and the promotion of innovative and personalized tourist experiences are all necessary steps towards increasing islands’ resilience in case of future economic downturn or health-and environment-related crises.