The park comprises 120 acres (49 ha) along the Pacific Ocean on the Clatsop Plains.
The 46 foot (14 metres) endangered mammal was underweight and had been entangled in rope.
It was only the second fin whale to be recorded as washing ashore in the state in 30 years.
The National Oceanic and Atmospheric Administration (NOAA) cautioned visitors to remain out of distance from the carcass due to needs for a necropsy and concerns of disease.
This Clatsop County, Oregon state location article is a stub.