Police are treating the death of a man who was found dead inside a cabin at a caravan park south of Adelaide as suspicious.

Emergency services were called to the Big 4 Port Willunga Tourist Park on Tuit Road at Aldinga about 2:15pm.

Police said that at the same time another man “presented himself at a police station”.

Detectives are questioning that man.

Police said members of the Southern District CIB are on scene, while forensics and crime scene investigators will also assist in the investigation.

“The scene has been secured and the public are asked to avoid the area,” police said in a statement.