The significance of the turning in the path in this story lies in the way that it has two paths that stem from it, one going to the "safe" beach where his mother and other tourists go, and one leading to the "wild bay" where Jerry finds the tunnel and sees the other French boys. Consider how the opening paragraph in this excellent short story points towards the importance of the turning in the path:
Going to the shore on the first morning of the vacation, the young English boy stopped at a turning of the path and looked down at a wild and rocky bay and then over to the crowded beach he knew so well from other years.
It is of course important to note the way that the "wild and rocky bay" symbolises Jerry's desire to be independent from his mother, whereas the "safe" beach represents his continued dependence upon her. Thus we can see that the turning in the path is very significant of the two choices that Jerry has before him. He either remains dependent upon his mother or engages in the struggle for his own independence, symbolised in the more dangerous bay where he finds the tunnel.