Sky Island: Being the Further Adventures of Trot and Cap'n Bill after Their Visit to the Sea Fairies is a children's fantasy novel written by L. Frank Baum, illustrated by John R. Neill, and published in 1912 by the Reilly & Britton Company—the same constellation of forces that produced the Oz books in the first decades of the twentieth century. The book was dedicated to the author's sister, Mary Louise Baum Brewster.