New Delhi, July 21 -- SCHOTTY BOY, as he is known online, is a hiking evangelist. He posts dispatches from the Scottish Highlands-moody, misty pictures of streams, glens, lochs and hills-to his more than 100,000 followers on Instagram and TikTok. In these posts, he is usually toting sensible walking gear such as a backpack, flask and an anorak. Sometimes, and inexplicably, he is topless.

He is one of many young people discovering the pleasures of the great outdoors. (As one TikTok video puts it: "Texting is cool, but hiking together is cooler.") Millions of posts extol the virtues of this cheap, accessible form of exercise. Some influencers recommend scenic routes, way stops and refuges. Apps such as AllTrails make it easy to find footpa...