Mrapen (Indonesian: Api Abadi Mrapen) is the name of an eternal flame that is the result of natural geologic activity. The Mrapen eternal flame is located in Manggarmas village, Godong District, about 26 kilometers from Purwodadi Grobogan district, Central Java, Indonesia. This eternal flame was created through natural geological phenomena; the leaking of natural gas from the ground. It was unknown when the gas leakage was ignited, but the Mrapen flame was already known in the 15th century Demak Sultanate era. It was mentioned that the sacred kris heirloom dagger of Demak Sultanate was forged in the Mrapen flame. The flame never extinguishes, not even in the middle of rain or winds.