We spent 3 weeks in North and South island and this was the best activity we did. A small group of just 2 of us got the chance to squeeze through tiny gaps and duck underwater to get through certain places all whilst being in an environment covered in glow worms.
It was an excellent mix of scenic and scary. We had Chan and Luke guiding us and they even let us do extra challenges again because we enjoyed them so much.
Would recommend to anyone in the area.