Researchers are piecing together what they know about Auckland's extensive network of rare lava caves.
Tāmaki Makaurau is built on a large, potentially active, volcanic field made up of 53 volcanoes.
There are at least 200 known lava caves, some reaching almost 300 metres long, and the sites are culturally and spiritually significant to Māori.
Auckland University masters' student Jaxon Ingold is documenting their locations.
Ingold spoke to Ingrid Hipkiss.