Quote a statement of Jerry's that shows how determined he is to swim through the tunnel.
After Jerry watches the older boys who shun him for being one of the foreigners and too young, he wants to swim through the tunnel as they have done. But, first he must find a way through it.
All night the boy dreamed of the water-filled cave in the rock, and as soon as breakfast was over he went to the bay.
The next day, Jerry exercises his lungs; it were as if everything "the whole of his life, all that he would become, depended upon it." Jerry practices holding his breath and measures how long he can do so by the big clock in the villa. When he can hold his breath for two minutes, Jerry figures that he is almost ready. Then, when his mother announces that they must leave in four days, Jerry tells himself,
On the day before they left, he would do it. He would do it if it killed him, he said defiantly to himself.
Ironically, Jerry chooses another moment--that one after his nose bleeds in practice--because he knows that if he does not go then, he will never attempt swimming the tunnel. Putting on his goggles, Jerry fills his lungs with air, and plunges to the bottom.