After swimming through the tunnel successfully, Jerry has completed his rite of passage and feels that to go again would be a superfluous act since he has proven that he is no longer a boy who is too soft to be able to hold his breath long enough to swim the length of the tunnel.
Jerry has proven to himself that he can do things on his own, away from his mother; he has also proven that he can compete with the older boys, that he has passed through the barrier that has separated the native boys and himself, the barrier that has made him cry. With his goggles Jerry has practiced holding his breath until he feels that he can stay under long enough to pass through the tunnel. After experiencing the victory of his act, Jerry sees the boys diving and fooling around:
He did not want them. He wanted nothing but to get back home and lie down.
By overcoming great obstacles and facing danger alone, Jerry now has acquired a greater maturity and a degree of independence. When his mother returns, he proudly tells her he can hold his breath under water for almost three minutes.