An eleven-year-old English boy named Jerry and his mother are on vacation at an unidentified foreign beach. Jerry’s mother is a widow and she is now struggling to provide both the supervision that a boy needs and the independence that she recognizes is going to become ever more important in his development. This declaration of independence takes the form of Jerry deciding to explore a rocky area of the beach while his mother goes to another more populated beach.
While swimming among the rocks, Jerry sees a bunch of older brown-skinned boys speaking in a foreign language. The boys remove their clothes and dive into the water from the rocks. As Jerry watches with interest, the boys each disappear beneath the surface, but do rise again as expected. Jerry begins to count, waiting for the inevitable bobbing head to break through the water that never comes. He begins to panic as they boys remain underwater without resurfacing for a dangerously prolonged period. Then, suddenly and to his relief, they reappear as if by magic on the other side of the barrier. His own dive into the water to figure out the trick only results in seeing a black wall of rock. Feeling ashamed of his own failure, Jerry attempts to childishly gain the boys' attention, but they continue to ignore him and eventually leave for another beach.
Determined to discover and replicate their feat, Jerry shows up at the rocky beach the next day outfitted with a pair of goggles he talked his mom into buying to assist in his underwater exploration. The process of discovery is slow and painful as he realizes he does not possess the lung capacity to make it through the tunnel. Weighing himself with rocks, he sinks to the bottom to practice holding his breath as his desire to make it through the tunnel transforms into compulsion.
Once his mother announces they will be leaving in another four days, he decides his must make it through the tunnel before they leave. Back at the rocks, fear overcomes him and he makes a resolution that he will have to wait another year to do it. But he rejects that resolution and instead decides to try to swim through the tunnel even though his nose is bleeding and his head is throbbing.
The passage is psychologically and physically exhausting, bringing on both imagined fears and actual injuries. Still, he pushes onward and makes it through the tunnel. Exhausted and proud, he no longer feels the desire to play with the older boys. Instead, he returns to the villa he shares with his mother, who questions him about his haggard appearance. She cautions him not to swim anymore for the rest of the day, and he, to her surprise, agrees. Jerry no longer feels compelled to explore the rocky beach.
