The world famous Waitomo glow worm caves are a fragile environment which need protection from the thousands of tourists tramping through each year.
This is where the man tasked with protecting them, Karl Fisher, comes in.
"The better the water quality you have the more insects and the more diverse insects you have in the stream.
"But glow worms are our core business, that's what people come around the world to see," Mr Fisher told TVNZ1's Seven Sharp.
It's a real balancing act, as the caves rely on tourists, but they're also the biggest environmental challenge.
"We are exhaling air enriched in carbon dioxide. In a confined space like a cave that carbon dioxide can accumulate and combined with water which will potentially corrode the limestone," Mr Fisher said.
The Waitomo Caves have been welcoming tourists for 125 years.
Hopefully Mr Fisher's stewardship means the glow worm caves will remain open for many more generations to enjoy.