The discovery was made at about 10.15am this morning.
Police have not given any indication to the age or identity of the man but have said the death is not thought to be suspicious.
Officers were called to the discovery of the body on the banks of the Afon Cain. They say an investigation is now underway.
A spokesperson for the police said: "The Coroner has been told. There do not appear to be suspicious circumstances at this time and the next of kin have been informed."