Gao jing really saw a ghost in the sea, that's what caused her to panic and accidentally injured her boy friend. the spirits, which were her boyfriend and the ghost in the sea, really lingered around her when she was in a mentally ill state. it's not just mental illness and hallucination in the film, but element of ghost as well, her bf spirit stopped the vid3eo recording she's playing to prevent her to know the truth. the ghost in the sea, the bf and gao jing's fate intertwine when she the accident happened in the sea.