What breakthroughs has Jerry achieved by the story's end?
In Doris Lessing's short story, "Through the Tunnel," Jerry, an eleven-year old boy, and his widowed mother go on a seaside vacation. It is during this vacation that Jerry discovers his own identity and learns to accept himself for who he is.
At the onset of the story, Jerry goes to the safe beach with his mother, yet he continually longs for the "wild and rocky bay." When he finally ventures to the bay, he meets a group of local boys. These boys are wild and free as some of them begin "stripping off their clothes." Jerry perceives these boys as men and longs for their acceptance, which he does not gain. Ironically, even though he wants to be part of their group and grown-up, when he swims far out, he searches for his mother on the beach, "a speck of yellow under an umbrella." Jerry is still a child.
However, Jerry watches the local boys swim through a tunnel, holding their breath longer than Jerry could ever imagine. Swimming through the tunnel becomes Jerry's challenge. He trains himself to hold his breath, and by the end of the story, he manages the feat. It has required pain and the loss of blood, a symbol of the price he has to pay to grow-up. Through this rite of passage, Jerry literally swims through the tunnel from childhood to manhood. He no longer needs the acceptance of the other boys; he accepts himself for who he is. This is his breakthrough.
On a basic level, Jerry has accomplished the physical feat he set out to complete. He has conditioned himself to be able to hold his breath for several minutes and overcome his fears to swim through the tunnel in the rock: an unbelievably dangerous and difficult thing.
Further, Jerry no longer craves the acceptance of the older, local boys with whom he so much wanted to fit when he first went to the wild bay. This is pretty significant. He attempted such a dangerous feat because they were doing it, and he felt childish and rejected when he could not do it before. However, he no longer links this experience to their recognition of him as an equal. This lack of concern for what they think is an achievement, as it shows the maturation that has resulted from Jerry's dangerous experience. He has also developed the ability to delay gratification, something he couldn't do at the beginning (consider his behavior when he wanted goggles). But now, he's developed "A curious, most unchildlike persistence, a controlled patience," and this is definitely the sign of a mature person.