This is my favourite bushwalk in New Zealand! Great value for effort.
This walk loops through the bush and takes about 45-60 minutes to explore the natural tunnels and caves, glow worms (at night) rivers and bridges. There are a few stairs but overall very family friendly and a great road trip stop to stretch the legs.

Here's a reel I shared on Instagram about this location: https://www.instagram.com/p/C_4uPpaSav4/