With the return of global travel in the wake of the COVID-19 pandemic, destination marketers face the major challenge of attracting tourists via advertisements in an environment characterized by fierce competition and comparatively limited budgets after a long hiatus. This research examines the effectiveness of different activity-based destination advertising tactics in crowded environments. Advertisements promoting tourism activities are poised to be particularly effective in the post-COVID-19 landscape, as tourists now prioritize experiential activities after enduring years of restrictions. This research shows that social crowding influences people's reactions to advertisements promoting different activities (relaxing vs. challenging). Specifically, in more (vs. less) crowded places, people are less (more) likely to be attracted by challenging (relaxing) activity-based advertisements because crowding triggers risk aversion. More importantly, promoting challenging (relaxing) activities with a loss (gain) frame triggers positive reactions to advertisements in a crowded environment.