What did Kino do at the end of the book?

Kino finally throws the pearl back into the sea. He does what Juana tried to do before the events that would lead to his baby's death. Kino has lost his son who has a value far beyond any pearl. Kino wants to rid himself of the greed and evil that the pearl has brought to his life. The money that the pearl might bring becomes irrelevant now that his family is destroyed. Profiting from the pearl at this point would only symbolize the death and blood of his baby. Throwing the pearl back is all that he can do now.