I inch my way down the steep path that skirts the wild rose bushes, down slipping along the wet grass where the underground stream seeps through the earth. My shoes are mud-clogged again. At the very bottom, I come to the bank. Above the trees, the moon is a pure white stone. The reflection is rippling in the river--water and stone dancing. It's a quiet ballet, soundless as breath.
Up at the top of the slope, I can see the spot where Uncle sat last month looking out over the landscape.
"Umi no yo," he always said. "It's like the sea."
Between the river and Uncle's spot are the wild roses and the tiny wildflowers that grow along the trickling stream. The perfume in the air is sweet and faint. If I hold my head a certain way, I can smell them from where I am. (39.17)
Did you ever notice the date that Naomi and Uncle go to the valley every year? It's August 9. On August 9, 1945, the atomic bomb was dropped on Nagasaki. When we see the first version of the scene in the beginning of the novel, we don't really understand what's going on. Why does Uncle want to go out in the middle of the night to a valley? Why does he think that it looks like the sea?
But by the ending we know the answers to all these questions. He wants to go to the valley to honor Naomi's mother. And he thinks that it looks like the sea, because it's the closest thing that they have to the sea in the town of their exile.
Naomi has spent the whole novel asking questions, and this ending shows us that she finally has the answers. She's not asking questions anymore. She finally understands all the things that she's been searching for this whole time.