Performance enhancement is the main reason why sportspeople do natural altitude training. However, the sportspeople's perception of this type of altitude training and the literature in the field of mountain sports tourism suggest that other reasons for natural altitude training might be identified. The objective of the present work was to discover the structure underlying a sportsperson's reasons for natural altitude training. To this end, we conducted an exploratory study (with 290 participants) and a confirmatory study (with 116 participants). A three-factor structure of reasons for natural altitude training was found, with factors called "Mountain environment" (3 items), "Openness" (3 items), and "Performance focus" (3 items). The results of our exploratory study might have applications in sports coaching and mountain tourism and might open up research perspectives in sports psychology and mountain sports tourism.