The Waitomo and Ruakuri Caves are located in a region of abundant limestone rock. The cave structures we see today began forming around 30 million years ago from the bones and shells of marine fossils, which hardened into sedimentary rock after collecting on the sea floor.
As the earth shifted and volcanoes erupted, huge slabs of limestone were lifted out of the sea. Over time, water flowed through cracks in the rocks, widening these channels until huge caverns were formed. There are approximately 300 known caves in the Waitomo region.
The stalactites, stalagmites and other cave decorations you can see in the caves are limestone crystal deposits, created as water drips from the roof or down walls. It takes hundreds of years for these decorations to form. For this reason it is important that visitors to the caves do not touch the formations, as they are fragile and easily discoloured or broken.
Find out more about Waitomo Cave decorations.