In the book hatchet what cause Brian to cry until he was all cried out?

In "Hatchet," Brian cries until he is all cried out after grappling with the overwhelming loneliness, fear, and despair of his situation following the plane crash. The isolation in the wilderness, combined with the trauma of losing his friend and the burden of his parents' divorce, brings him to an emotional breaking point. This cathartic release allows him to confront his feelings and ultimately find a sense of resilience and determination to survive.