JOMBLANG CAVE

A 40m deep single-shaft with a diameter of 50 m formed by dissolution and collapse of 15-2 million old limestone. This occurred after the limestone was uplifted from the sea floor about 1.8 million years ago. The bottom of the collapsed sinkhole is connected with a horizontal passage that ends at Grubug Cave. Grubug Cave, a single shaft of about 90m, is the deepest vertical cave in Java Island. The phenomenon of Grubug underground river and the upward view from the bottom is very amazing