David is a 14-year-old boy living in Ventura who is grieving the recent loss of his beloved uncle to cancer. Tasked with scattering his uncle's ashes out at sea, he boards his inherited sailboat and impulsively heads into the open water without checking the weather or his supplies. He feels things deeply and candidly, which leaves him vulnerable to waves of anger and fear when he finds himself lost on the Pacific Ocean.

Owen is David's recently deceased uncle, remembered as a broad, strong, and boisterous man. He was a passionate sailor who kept only the bare essentials on his boat, scorning the use of its motor in favor of wind power. He harbored a deep thirst for knowledge about the ocean and the world, and his practical lessons serve as David's primary guide for survival.

The Frog is Uncle Owen's dependable sailboat, left to David as a dying wish. Initially acting as a painful reminder of Owen's death and a makeshift funeral barge, the boat quickly takes on a life of its own. The vessel serves as David's literal shelter and assumes the role of a steadfast companion during his harrowing journey on the Pacific.