Tourism is affected by social, political, economic, technological and environmental changes at all scales. Population growth, redistribution of wealth, geopolitical changes and conflicts, rising fuel costs, climate change and its consequences, new technologies and work patterns, and all forms of social fashion influence who wants to travel where, for how long, to do what, and at what prices. Here, we examine six large-scale exogenous trends for the global tourism sector over the next 30 years: (1) The social, economic and environmental consequences of gradual warming and of extreme weather events associated with climate change; (2) The effects of higher fuel costs and social concerns on mass long-haul travel; (3) The role of new technologies, including social media, in marketing, managing, experiencing and monitoring tourism; (4) Economic growth and social change in the highly populous and newly wealthy BRICS nations, especially India and China; (5) The consequences of armed conflict and geopolitical negotiation for tourism, and the use of tourism as a tool for geopolitical interests; (6) The increasing linkages, and also conflicts, between tourism and conservation in many countries. Improved understanding of these megatrends, and the interactions between them, are priorities for future tourism research.