To advance the theoretical and practical underpinnings for nature therapies, i.e. nature exposure as a means to improve mental health, we compared the most memorable sensory experiences reported by forest tourists in Australia, Chile, China and Japan. Sensory experiences are a fundamental driver of the psychological effects of nature exposure. We first reviewed relevant research from each country and language. We then conducted 100 on-site interviews in Australia, 100 in Chile, and >500 in China, and compiled 1000 relevant social media posts from Japan. We analysed these datasets using directed-content qualitative thematic analyses, both in original languages and in translated texts, and compared outcomes from each country. The key sensory experiences are universal: sights of plant shapes and colours; sounds of birdsong, running water and rustling leaves; smells of flowers, trees, and earth; taste and temperature of clean air and water; and touch of bark and rocks. Participants gave detailed descriptions of each. These fine-grained but widespread experiences are our principal finding. These sensory experiences are at a scale that is broad enough to apply for prescriptible nature therapies in any forested region, but fine enough to be used in future quantitative research to test therapeutic designs, doses and durations. This distinguishes them from prior research, that is either too broad or too fine in scale for practical therapy design. Future research aiming to maximise the mental health benefits of nature may not need to distinguish different countries and cultures, but may need to differentiate nature experiences more finely and precisely than in most therapy-related research to date.