Ijen Crater is the biggest crater lake in Java. The sulfur crater lake lies between a natural dams of deeply etched rock. It is 200 meters deep and contains about 36million cubic meters of steaming acid water, shrouded in a smelling swirling sulfur cloud. Inside the crater the different color and size of stones are found. Indeed the crater of Ijen is beautiful garden of stone as well.
The Ijen Plateau lies in the centre of the Ijen-Merapi Maelang Reserve, which extends over much of the mountainous region directly west of Banyuwangi and borders on the Baluran National Park in the north east. As at Mt. Bromo , the caldera is best viewed from the air. Fortunately, almost all commercial flights operating between Denpasar – Surabaya, Yogyakarta or Jakarta usually fly, if not directly over, then close by Ijen plateau, where the seemingly luminous blue/green crater lake forms an unmistakable landmark. It is a beautiful scenery and located about 32 km to the north west of Banyuwangi.
The principal attraction at Ijen is the large, sulphureous crater lake which lies hidden between sheer walls of deeply furrowed rock at more than 200 meters. The Ijen crater itself lies at approximately 2,300 meters above sea level. It forms a twin volcano with the now extinct Mount Merapi. The enormous crater lake, which is 200 meters deep and covers an area of more than meters, a million square meters, contains about 36 million cubic meters of steaming, acid water.
Ijen crater shows a special type of volcanic feature common to Indonesia, about 1 kilometer in diameter and 175 meters deep. The floor is covered completely by a warm lake, milky blue green in colours held back by a dam built many years ago by the Dutch, in order to keep the hot, mineral laden water from raining the crop lands below.
The crater can be reached from either the east or the west by any kinds of vehicles, but the second part of the trip covers distance 3 km on foot (jungle track). However, the latter is more popular approach, since the climb from the road’s end to the edge of the lake is only one and a half hours. And a walk around the lake takes a full day.
The temperature drops at night, near the crater rim it can fall to about 5° Celcius. The road ends at Jampit, where very basic shelter is available. It is also possible to sleep in the old vulcanology station further up the hill, now used by sulphur collectors, but permission must be obtained in advance.