When the time comes for Karana to leave the island, she makes the transition from her own leisurely and personally subjective sense of time to that in which the rest of the world lives. The return of the white men jars her understanding of where she has been and where she is going. Before, when she was alone on the island she had always known what she needed t do, now, as she leaves for a world inhabited by people, she is confused. "I could not think what I would do when I went across the sea," she says. Just so, we realize how much time Karana has spent on Ghalas-at. The years had melded one into the other for Karana and the reader, but Karana has now grown from a girl to a woman. She thinks of this and smiles as she makes the sign on her face that means she is unmarried.
When Karana marks her face to signify that she is not yet married, she remembers her sister Ulape doing the same thing many years before. Then, Karana had watched her sibling with amusement; now she watches herself with similar amusement. Making the mark on her face, however, reveals Karana's hope for her life across the sea. She has the chance for a new life there, to see her people again and maybe to build the family she has always wanted.
The hope that Karana feels on leaving the Ghalas-at is expressed as a general tone at the very end of Island of the Blue Dolphins. As Karana sails away from the island, dolphins come and swim with her ship. Remember from chapter ten that dolphins are "animals of good omen," that they gave Karana the spirit to make it home after her unsuccessful attempt to leave Ghalas-at. Before, they lead her home, and when she reached her island she realized just how happy she was there.