In reply to Fredt:
Tintin in Tibet.
Child entered accounts of real adventures, for example Michel McCurdy's Trapped by the Ice - an account of Shackleton's famous rescue endeavour.
In a year or two, the whole of the Swallows and Amazons oeuvre. A bit much for a ten year old, but not far off, and their memory remains with me as the essence of adventure.
Anything else that gives your grandchild a sense of adventure unbound. For me at that age that included books about Vikings and their voyages, especially the novels of Henry Treece.