Did you know that approximately 20 million years ago, Izu was located on the bottom of the Pacific Ocean, far from the island of Honshu? It is believed that at that time, Izu was a collection of undersea volcanoes in the vicinity of Iwo Jima. This group of volcanoes moved north along with the Philippine Sea Plate. one million years ago, they began colliding with Honshu, becoming a peninsular form similar to Izu’s current shape 600 thousand years ago. The abundant hot springs and unique scenery found across Izu were created through this geological activity stretching back to ancient times. The products of past volcanic activity as well as the effects of the continuing movement of the local geology can be seen in a variety of locations around Izu.
Official Izu Travel Guide