I've been to Lake Rotomahana, saw a number of signboards with illustrations. It never occurred to me that the terraces might still be in place.

FWIW, the illustrations you see are colorized B&W photos as color photography was yet to be a thing. OTOH, the terraces didn't move, making them a good subject for the photography tech then available. There are some B&W photos here.

Also, if you've never been to NZ, just go. It's still amazing. If you've seen Peter Jackson's Lord of the Rings, yeah, it looks just like that.