Tourism is a large, diffuse global industry. Environmental aspects are little studied, with ∼1,500 publications in total. Impacts range from global contributions to climate change and ocean pollution to localized effects on endangered plant and animal species in protected areas. Environmental management is limited more by lack of adoption than by lack of technology. Government regulation is more effective than industry-based ecocertification. In developing nations, tourism can contribute to conservation by providing political and financial support for public protected area agencies and for conservation on private and communally owned lands. This is important in building resilience to climate change. In developed nations, such effects are outweighed by the impacts of recreational use and by political pressures from tourism property developers. These interactions deserve research in both natural and social sciences. Research priorities include more sophisticated recreation ecology as well as legal and social frameworks for conservation tourism.

Poor mental health costs about a tenth of global GNP. For many people, nature exposure improves mental health. This generates a newly recognised health service value for national parks worldwide, estimated at trillions of dollars annually. It creates a correspondingly large potential new market for commercial nature tourism, as a provider of nature therapies, especially in national parks. Before this opportunity can be realised, however, we must establish whether voluntary park visits generate mental health gains for everyone. Currently, psychology researchers and protected area managers hold opposing views. I therefore interviewed 238 outdoor nature and adventure tourists of all ages and backgrounds, at subtropical national parks in Queensland, Australia, to determine whether they visit parks because they are happy, or they are happy because they visit parks. A large majority, 82%, picked the latter. Of those asked, 87.5% reported short-term emotional benefits; 60%, medium-term recovery from stress; and 20%, long-term changes in worldview. Each timescale corresponds to a different opportunity for commercial nature tourism. Future research priorities include: economic scale; experiential components and commercial design for different market segments; comparisons of individual benefits for people with different personalities; and tests of mental health benefits for other types of tourism.