 According to legend, there was a man living in the mountains who assaulted his granddaughter and was punished by the mountain deities for his disrespectful act by flooding the area forming the Lake Apo.The lake is a crater lake, a basin formed on an old volcanic cone that was later filled with water.It was erroneously reported as a circular rift lake, as this area is not a rift zone but a volcanic area evident by the presence of nearby volcanic peaks like Musuan Peak ( to the E), Mount Kalatungan ( to the NW), Mount Dagumbaan ( to the SW), Mount Kidongin ( to the SW), and the volcanic field east of Pangantucan, Bukidnon ( to the west).