As Bilge Rat has written, we were on the way to our first LOTR location on the South Island: Chetwood Forest.
Chetwood Forest is located near the top of Takaka Hill near the Ngarua Caves, where you can look at some Moa skeletons (extinct giant walking birds). A word of caution. There are cave tours called "Ngarua Caves - A Middle-Earth Experience" advertised with images of the one ring. Neither the cave, nor the tour has anything to do with the Lord of the Rings. The operators just want to catch some LOTR location hunters, that's all. When I enquired about the name, they simply said: "Well the cave takes you to the middle of the earth, doesn't it? Also some scenes of LOTR were shot in the rough vicinity around here."
Our advice: Go for the "rough vicinity" in the first place and skip the caves, 'xcept if you want to see some Moa skeletons...
Anyway, we took the next exit on Takaka Road and followed the unpaved road for several kilometres. We actually passed and missed Chetwood Forest and ended up at the beginning of a walking track leading to the spectacular Harwood's Hole.
On the way back, of course we made a stop at the forest. Chetwood Forest is where Strider lead the Hobbits into the wilderness after leaving Bree. Here are some images of Chetwood Forest: