Mount Cameroon has the most frequent eruptions of any West African volcano. The first written account of volcanic activity could be the one from the Carthaginian Hanno the Navigator, who may have observed the mountain in the 5th century BC. Moderate explosive and effusive eruptions have occurred throughout history from both summit and flank vents. A 1922 eruption on the southwestern flank produced a lava flow that reached the Atlantic coast. A lava flow from a 1999 south-flank eruption stopped 200 m (660 ft) from the sea, cutting the coastal highway.