So when in New Zealand, you must do something adventurous because that is what the entire country is about! There are bungee jumps, parachute jumps, etc everywhere! We decided to join an underground tour that took us zip lining, and rappelling into a dark glow worm cave near at Waitomo caves.
The tour company we went with was Black Water Rafting co and we chose the Black abyss tour which was their longest and strenuous one they had. We have found out that if you are booking, there are several sites and all of them are around $250 but in different currencies. Definitely shop around to see which one works out the best for you, we chose to buy it in New Zealand Dollars because the currency conversion rate was in our favor.
Before the tour started, we were outfitted with wet suits and given a quick crash course on how to rappel down into the caves. We had two knowledgeable tour guides that helped us navigate through the caves because it is very easy to get lost down there. We also weren't allowed to bring our own cameras so they became out personal photographers as well! They also carried our lunches for us which included some nice hot chocolate which was amazing when you are wading in sometimes waist deep water.
Once we were down in the caves, we walked through most of it but we did get to zip line down into pitch black darkness and also jumped about 15 feet down into cold water with inflatable round floats. Of course we got some pictures taken by the tour guide!
After the tour was over, we got to take a nice hot shower and went to the cafeteria for free hot soup. That day we had tomato soup and after 5 hours being down in the caves, the tomato soup was probably the best thing to come back to!
I highly recommend doing this if you can still handle it!