At the eastern tip of Java – Indonesia, a large caldera region stretching from the catastrophic eruption of an old giant volcano during the Pleistocene geological period, making it the largest caldera in Java with a diameter of 20 km. The complex consists of dozens of small, extinct stratovolcanos, among them formed the crater. With a wide panorama of mountains and natural, it’s no wonder that this region has become a popular tourist destination. Ijen Crater, the only phenomenal crater  with the  most acidic crater lake in the world, making many people to travel here.