The lesser-visited cave that you can combine with a visit to the famous glowworm caves. It's only possible to visit with a guide and tours take about 1-1.5 hours. In our opinion this is the more relaxed option with a smaller group. The glowworms are as vibrant as in the other cave, and unlike at Waitomo Caves, you're allowed to take picture inside here. Highly recommend!
An alternative way of exploring this cave is by going on a black water rafting tour! We didn't do it ourselves, but did see a group coming by. It looked pretty cool and unique!