The healthcare sector recognises the role of nature in mental health. The tourism sector is equipped to take people to national parks. The conservation sector gains support from visitors. Theoretical frameworks for mental health benefits from nature tourism include: tourism destinations and activities; tourist personalities and life histories; sensory and emotional components of tourist experiences; and intensity and duration of memories. Mental health deteriorated worldwide during the COVID-19 pandemic. Recovery of global economic productivity requires immediate, accessible, affordable mental health measures at national scales, and nature-based approaches provide the best option. Different countries have adopted a variety of public, private, or voluntary mechanisms. Some focus on design of activities, others on provision of facilities. Costs and implementation depend on key research questions: marginal benefits of nature tour guides or psychologists compared to self-guided nature experiences; comparisons between repeated brief visits and one-off nature holidays; effects of biodiversity, flagship species, and scenic or wilderness quality; and differences between individuals, depending on personalities, life histories, and mental health status and symptoms.