Shmuel Yosef Agnon (Hebrew: שמואל יוסף עגנון, July 17, 1888 - February 17, 1970) was a Hebrew nobel prize laureate writer and was one of the central figures of modern Hebrew fiction. In Hebrew, he is known by the acronym Shai Agnon. In English, his works are published under the name S. Y. Agnon.

In the Heart of the Seas is a sophisticated fantasy that tells the story of a pilgrimage of a group of Hasidim to the Holy Land. During an early decade of the nineteenth century in Bucsacz, S.Y. Agnon's actual birthplace, a small group of pious townspeople decides to sell their property and belongings, put aside their business affairs, and make their way to the Holy Land to spend the remainder of their days in study and prayer.

The pilgrims are joined by a simple Jew by the name of Hananya, who carries all of his possessions in a kerchief and who has encountered many obstacles and privations in his longstanding efforts to reach Jerusalem. He not only completes their minyan but also drives one of the wagons and provides the practical know-how that enables the faithful to negotiate the long journey from Eastern Europe to Constantinople.

Along the way many Jewish settlements are encountered and described and many legends about the Holy Land are told. Hananya is late to the ship's departure from Constantinople to the Holy Land because he is busy reading the Agunah, and unaware of his absence, the faithful embark upon the tempest-tossed voyage without him. When they arrive in Jaffa, Hananya is there before them, having flown over the seas transported on his "magical" kerchief. Settled in Jerusalem, the members of the group experience a mixture of fates, and it is only Hananya who lives to a contented old age.

Named by Harper San Francisco one of "The 100 Best Spiritual Books of the Twentieth Century" and among Harold Bloom's selections for The Western Canon: The Books and School of the Ages.