"Are you ready?"
He thinks, yes.
He thinks, Go in swinging.
And he says, "I'm ready."
He is standing on the beach. Even in the middle of summer, the wind is icy and he feels as if his skin has been dipped in acid. It takes him a moment to realise how he got there. He's vaguely aware that he was going into the water, but then he wonders why. After all, it was freezing even without the addition of water.
Then he remembers. Gudmund, Owen, Valentine, his parents, Lethe, Regine and Tomasz. Everything becomes clear. And Seth, as he figures out his name, sighs with relief. He remembers. It worked.
So he turns away from the sea, and starts to walk home.