Anyone who opens a physical map of Java will notice immediately the high, mountainous ridge extending along the entire lenth of the centre of island. Some of the higest and nost active of these volcanic peaks are to be found in East Java, whose flat, fertile plains are punctuated by no less than six separate ranges, becoming progresively higher toward the east. These mountains are among East Java's principal attractions and some of the more outstanding include the 3,676 meter active cone of Mt. Semeru, Java's higest peak, the famous sand sea and steaming crater of Mt. Bromo, the sulphureous summit of Mt. Welirang and the strangely beautiful crater lake of Ijen and Kelud. Two main waterways, Brantas and Solo rivers are lifelines for much of East Java predominantly agricultural community. The former rises in the highlands to the north west of Malang and follows a circuitous path before dividing into  a number of smaller streams to meet the sea a  Surabaya. The famous  Bengawan Solo, longest river in Java, has its source in the centre of the island and stretches 540 kilometers before joining the coast at Gresik. Other important rivers include the Madiun, Konto, Sampeyan and Grindulu.