Access

4.5 km south of Morere and 3.5 km from Nuhaka, turn into unsealed Mangaone Valley Road. After 6.5 km, just after the crest of the hill, there is a parking bay on the right, opposite the signpost to the start of the track.

Track

The track is a poled route over farmland, which is private property. The initial section is very steep and will require zig-zagging to avoid the walk being a non-starter.

After crossing the bluff the track is easier going over the grassed hilltop and enters the scenic reserve through a gate.

The entrance to the cave is a 4-metre high portal and aided with steps. These can be lethally slippery when wet. Obviously, exploring the caves will require a torch and if you have a hard hat or cycle helmets kicking around the garage, then bring those too.

The total length of the passages in this system is approximately 2.1 km. The main cave is around 40 metres long, 9 metres high and is lit from both ends by daylight. However if you want to explore the two side passages, 3 m above the main cavern, you will need agility and extreme care at the top of the wooden ladders.

The first side passage dwindles in size and you need to crouch near the conclusion. The stalactites and stalagmite straws on the ceiling resemble a coral reef and the sculptures formed where stalactites and stalagmites meet are so intricate they defy the imagination. Don’t be tempted into a memento, as the tiny straws take lifetimes to form and already there is plenty of evidence of vandals picking them off the ceiling.

The second tunnel requires and act of contortion to squeeze through the initial opening, but once through it extends far enough to start making you wonder when it will end. Don’t let your imagination deceive you into thinking the calcite lumps on the ground are skulls and the drops of water are the impending approach of an axe murderer. Instead, be awe-struck by the walls of calcite and the bulbous stalactites, which resemble brains in their form. Fluted columns from startling sculptures and the crystalline cavern is like being in a fairytale.

Geology

The limestone and sandstone rock were formed around 2.5 million years ago in a shallow sea environment. The reef system contained many oysters, barnacles and scallops, which form noticeable fossils on the exposed bluff.

Subsequent tectonic upheavals raised the block above sea level and folded it to a sinuous, convoluted form. The Mangaone cave system lies on a syncline, the basin of a fold, and the weaknesses and fractures have since been exploited by water.

Rainfall dissolves and accumulates carbon dioxide into its molecular structure as it passes through the soil, which turns it acid. It dissolves the calcite from the surrounding rock and deposits is as straws, stalactites and stalagmites as it drips from the cave roof. The carbon dioxide is released to the cave atmosphere. These processes give rise to the amazing subterranean artwork on display.