The body of a slim, blonde man between 20 and 25-years old was found floating near Algar Seco beach in Carvoeiro, Lagoa.
The victim had severe head injuries and repeatedly had been stabbed in the chest and abdomen.
The victim's identity is not yet known and no documents were found on the body. No one yet has been reported missing in the area.
The body was transported to the Portimão where an autopsy will be performed to determine the precise cause of death.
A source from the maritime police said that the Judicial Police are now involved in investigating the death and have been showing local businesses photographs of the deceased to find out if anybody recognises the man.