Mountainous geographical domains often host many high-angle slopes (“walls”) that are linked to peaks, cliffs, and river valleys. Such slopes are ideal for (almost) extreme tourism, sport, and outdoor recreation activities that are very generally known as climbing, but can be also defined using several other terms (e.g., mountaineering (=alpinism) is the main alternative term for rock climbing, but climbing is preferred provisionally as the main generic term in this paper). Millions of more or less trained visitors to mountains are involved in these activities on an annual basis (rock climbing is paired now by indoor climbing).
Rock climbing usually means “conquering” notable peaks and cliffs (at least, reaching high points), often with a preference for challenging routes and non-trivial solutions; these activities can be linked to tourism, sport, and outdoor recreation [
42], and they require some physical training [
43,
44,
45], risk-taking and pleasure satisfaction [
46,
47,
48,
49], and specific geographical vision [
50]. Rock climbing also exerts a significant anthropogenic pressure on the environment, although the degree of this pressure depends on different parameters and conditions, and remains debatable [
51,
52,
53,
54,
55]. Mountaineering is a slightly more general term referring to the broader spectrum of tourism, sport, and recreation activities in mountainous domains; essentially, it refers to the same activities as climbing, although emphasizing the outdoor character of these activities [
42,
56]. The on-line bibliographical database Scopus includes >320 papers mentioning rock climbing in their titles and >380 papers mentioning mountaineering (state as at mid-May, 2020; some of these papers deal with geoheritage, but the majority do not). In the literature, mountaineering is often treated in regard to industry and society [
57,
58,
59] and places [
60,
61], but chiefly to personalities (physiology and emotions) [
62,
63,
64,
65,
66,
67,
68,
69,
70,
71]. Environmental effects are also documented [
72,
73]. Two other activities that are related to climbing are bouldering and canyoning. The former means short-distance, but difficult, route climbing on big boulders (megaclasts in geological terminology) or relatively small landforms (e.g., hillocks) with steep slopes. Bouldering is more a sport or outdoor recreation activity than tourism. In the literature, this activity is discussed in regard to human physiology and psychology [
74,
75,
76], and the landscape context [
77] and environmental effects of bouldering are also documented [
78,
79]. Bouldering sites also facilitate finding peculiar geological objects such as megaclasts [
80]. Canyoning is a kind of adventure tourism in difficult-to-access river valleys (chiefly, these are canyons and gorges) [
81,
82,
83,
84]. Partly, it is based on climbing, and steep slopes constitute its main resource. Development of canyoning is also related to the issues of risk-taking and safety [
85,
86].
Climbing activities are strongly related to sustainability. On one hand, they challenge the latter via an increase in the anthropogenic pressure on natural environments [
51,
52,
53,
54,
55,
72,
73,
78,
79]. On the other hand, these contribute to sustainable development via generating additional income and jobs, planning improvement, social and political stability, etc. [
87,
88,
89]. However, the role of extreme/adventure tourism in the achievement of sustainability should not be exaggerated [
90,
91,
92]. Moreover, local sustainability is a factor in the development of climbing activities (e.g., [
87]).