Warning sign at the trail head of the Pinnacles summit trail in Gunung Mulu National Park (Borneo Island)

The Mulu Pinnacles are Karstic rock formations in the shape of huge vertical sharp blades up to about 50 m (150 feet) high, in a remote rain forest over Gunung Api mountain. The Pinnacles were formed by erosion of the Karstic limestone rock forming the mountain.

For more photos and information about this amazing place, go to the Mulu Pinnacles photo series.