A missing teenager has emerged unscathed from bushland east of Melbourne in what his friends have described as "all part of god's plan."

Shane Richards, 18, was reported missing to police after walking away from his campsite at Toorongo Falls, Noojee, about 11pm yesterday.

It’s understood Shane fell into the river before going missing, meaning his clothes were wet as temperatures dropped below zero overnight.

His disappearance sparked a wide-spread search of the area surrounding the campsite from first light, involving SES members and the Police Airwing.

About six hours later, the teen emerged on his own and was quickly assessed by paramedics at the scene about 1.30pm.

“I got a bit emotional when he came down,” Shane’s friend, Bob, told 9NEWS.

Acting Sergeant Sean O’Donnell said emergency services were surprised at how well the teen was doing following the ordeal.

“He's safe and well and that's the best thing we can hope for,” Act. Sgt O’Donnell said.