Amanda Davidson

Wai’ is the Māori word for ‘water’, while ‘tomo’ means a hole in the ground.

The Waitomo Caves and neighbouring Ruakuri Caves are located in an area of abundant limestone rock. The cave structures we can see and walk through today began to form around 30 million years ago from the bones and shells of marine fossils. As they collected on the sea floor, they hardened into sedimentary rock. During this time the earth shifted and volcanoes erupted, causing huge slabs of limestone to be lifted out of the sea. Over the centuries, water flowed through cracks in the rocks, widening them into larger and larger channels until huge caverns were formed.

The stalactites, stalagmites and other cave decorations you can see in the caves are limestone crystal deposits, created by water as it 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 can easily be damaged.

Having trouble identifying the cave decorations inside Waitomo Caves? Stalactites grow downwards from the ceilingStalagmites rise up from the cave floorStalagmites and stalactites can join up to form columns or pillarsHelictites are spiral-shaped decorations

The Waitomo Caves were discovered in the late 1800s by local Māori chief Tane Tinorau, owner of the land on which they were located. Tinorau and a surveyor called Fred Mace explored the caves together in 1887, floating in on a raft of flax flower stalks. Tinorau later found an entrance on land, which is the same entry point we use today. In 1889 the caves were opened to tourists, with local Māori acting as guides. Many of the staff working at the caves today are direct descendants of Chief Tane Tinorau and his wife Huti, as the cave and its lands were returned to his family in 1989, after a period of government administration.

The glowworms found in the Waitomo and Ruakuri caves are the larvae of a species of gnat called Arachnocampa luminosa, which is unique to New Zealand. These insects spend most of their life as larvae (juveniles), growing to the size of a matchstick. Although the effect of their twinkling lights is beautiful, the glowworm itself actually looks quite like a maggot!

Glowworms glow because their tails are bioluminescent – the chemicals they produce react with the oxygen in the air to generate light. They spin sticky threads from the roof of the cave, and use the light from their tails to attract other insects and trap them in the threads for a tasty meal!

The Waitomo Caves are the perfect environment for glowworms, because they are dark, damp, and sheltered. This means the glowworms’ lights can be seen and their feeding threads don’t get dried out or damaged by wind. The river that flows through the caves brings them plenty of insects to catch. The caves are carefully monitored to make sure the glowworms have everything they need.

The nearby Ruakuri Cave is Waitomo’s longest underground guided walking tour and is also the only wheelchair-accessible cave in the Southern Hemisphere. Ruakuri is famed for its spiritual links to Māori and its incredible limestone formations and spectacular caverns.Read more