Organising an outdoor event in a venue which has been assigned as a National Park is subject to a far greater number of constraints than in a non-protected area. By using the example of the ultramarathon races across Reunion Island since 1989, this study aims at analysing the history of the event's ecological policies with regard to the special vulnerability of the region, and the changes in status of the concerned landscapes and tourism strategies. The method embraces a study of the existing literature on the history of both the event's organisation and the island's environmental policies over the past 24 years, combined with a press content analysis. The results demonstrate that the creation of a National Park in 2007 and the nomination of large parts of Reunion Island as UNESCO World Natural Heritage sites in 2010 indeed led to further nature conservation policies which were, from then on, followed empathically in order to harmonise ideas of nature conservation and event organisation.