In "Through the Tunnel" by Doris Lessing, how are the descriptions of the "wild and rocky bar" reflections of the story's protagonist?

Well done for observing this difference! There is
definitely a marked contrast between the wild bay and the safe beach where Jerry's
mother stays. For Jerry, however the "wild-looking" bay meets his need for danger and
his feeling that he has to exert his independence and show his maturity by going through
some kind of rite. The setting of this wild bay is incredibly important, as it is here
that Jerry discovers the tunnel and decides on the challenge that he is going to set for
himself. It is this desire to prove himself that causes Jerry to go to the wild bay,
rather than follow his mother to the safe beach, as she would like. Thus it is that,
after having gone once, we are told that "he did not ask for permission" the next day to
return there and he continues to exert his independence from her throughout the rest of
the tale as he prepares for his challenge.