Well, it seems that the words conjure an image of climbing on and over things, like huge boulders, or climbing across or through things, like streams.
Kids don t climb mountains they climb things on the mountain.
Then, there must be a host of interesting things to do or see along the way. Although you may think the goal is to get to the top of the mountain, most kids couldn t care less. You can t eat it, you can t crawl over it, you can t play with it. But if you can throw rocks off it or get close enough to the edge to make parents scream their bloody heads off . . . It's hard to top the fun to be had at a local swimmin' hole.