Research has found that sharks have an acute sense of smell and that's how they find their way home. They rely on their sense of smell to find their way back since they travel great distances. For instance, Great White Sharks travel from Hawaii to California. Moreover, many experiments have been conducted trying to prove this theory and the research shows its a plausible explanation; however, many scientists still hold the finding to be inconvincible. Those who oppose the theory argue that there must be other factors that guide sharks to find their way home and around the deep vast oceans.
http://news.nationalgeographic.com/2016/01/160106-sharks-leopard-smells-navigate-oceans-animals-science/
http://news.nationalgeographic.com/2016/01/160106-sharks-leopard-smells-navigate-oceans-animals-science/