The man, who has not yet been formally identified, was discovered in a wooded area near the Goodwyns housing estate in Dorking on Monday.
Surrey Police has been given more time to question a 21-year-old male arrested on suspicion of murder.
The force is awaiting the results of a post-mortem examination.
Extra time has been granted to detectives quizzing a murder suspect over the discovery of a body in a stream.