According to the Thurston County Sheriff's Office, the boy's body was found near Beverly Beach around 8:30 a.m. Tuesday.
Deputies say the boy had autism and frequently would leave the home to wander. An adult in the child's home was asleep at the time the child left the home in the early morning hours and was unaware that he was gone.
The investigation is ongoing. The case has been refereed to Child Protective Services to ensure other children in the home are taken care of, deputies said.