Describe, in detail, the mother-son relationship at the beginning of the story "Through the Tunnel" by Doris Lessing?

Jerry is eleven years old when he and his mother vacation in a foreign country. It is a place they have been to before, since the narrator tells us that Jerry knew the crowded beach from years past. His mother is a widow and she may be quite aware that Jerry needs to assert his future manhood and individuality without her motherly interference. On this trip she seems to have made a conscious decision to allow him to explore and do more than just sit on the beach within her realm of influence. She feels that maybe she has been overprotective and she is "determined to be neither possessive nor lacking in devotion." While she is definitely worried about him as he strikes off to the wilder, rocky bay adjacent to the crowded beach, she wants to allow him to be on his own. She doesn't ask many questions about his adventures at the bay, not wanting to intrude into his life. She even agrees to buy him goggles for his swimming excursions. 

Jerry has a keen sense of devotion to his mother. The narrator comments that he was almost chivalric in his attitude, and though he is hesitant to leave her side, the prospect of adventure on the rocky bay is too much. He is lured to break away from her and strike off on his own, but even then he feels safe when he sees her figure on the beach. At the bay he discovers the foreign boys diving and emerging on the other side of the rocks by going through an underwater tunnel. From that point on he is determined to swim through the tunnel. He talks little about his time at the bay when he is with his mother. He is obviously concerned that she may forbid him from achieving his goal. As the days pass he stops asking her permission to go. He is almost fanatical in his determination to swim the tunnel. After his goal is met, he comes back to the villa pale and with a bruise on his head. Amazingly his mother takes it in stride: "Oh, don't fuss! Nothing can happen. He can swim like a fish."

Ultimately the relationship is one that many young boys would be overjoyed to have with their mothers. She allows him to be on his own, set goals, and conquer his fears. The swimming of the tunnel is Jerry's first step toward maturity and the mother is quite willing to allow her son to grow up on his own terms.