Directed by Joel Anderson, Lake Mungo (2008) is an Australian psychological horror film presented through interviews, photographs and home-video footage after the mysterious death of a teenage girl. The story follows her family as grief, secrets and possible supernatural evidence gradually reshape what they believe happened. The film combines mockumentary form, ghost-story horror and slow-burn psychological dread.

Sixteen-year-old Alice Palmer tragically drowns while swimming in the local dam and in the days that follow her grieving family begins to experience a series of strange and inexplicable events. Seeking the help of a parapsychologist, their search for answers reveals that Alice had been living a disturbed life and hiding dark secrets. Something had haunted their daughter and the terrifying truth awaits at Lake Mungo.

Från IMDB:
Strange things start happening after a girl is found drowned in a lake.