The objective of this study was to determine the numbers and percentages of various groups of visitors hiking off trail, the motives driving visitors to do so and the damaging impact on nature and the environment. Sections of eight routes in the Pieniny Mts. National Park (NP) were selected for the study. On average, 29.4 % of visitors were found to have strayed from the official routes, with children being the most prominent group (38.2 %). The groups led by guides left the trails significantly less than other groups (24.2 % and 30.5 % respectively). Technical reasons for leaving a trail, e. g. crowds or obstacles on the route, predominated over volitional reasons, such as taking photographs or resting (56.8 % and 43.2 % respectively). The proportion of persons walking off route drops significantly when the route has kerbs (Z = 2.10638; p = 0.0352), and a convenient trail surface (7.06311; p<0.0001). Additionally, a negative correlation was found between walking off the route and the mean (ρ = −0.2048; p = 0.0018) and minimum width of the route (ρ = −0.3244; p < 0.0001). A significant correlation was found between the type of habitat surrounding the route and the damaged surface (H = 37.4932; df = 2; p < 0.0001). In forest habitats, the breadth of the zone where vegetation was completely absent was significantly larger than in mixed habitats (Z = 5.35021; p < 0.0001), and non-forest habitats (Z = 5.35331; p < 0.0001). Similarly, in forest habitats the surface of the zone with damaged vegetation was significantly larger than in the remaining habitats (H = 154.7565; df = 2; p < 0.0001). The total length of informal trails branching off from the study areas was 242 m, which constituted 63 % of total length of the stages of the studied routes.