The container is hiding, in obvious sight. Once you see it, I guarantee opening it will be as easy as 123!
Plenty of room for swag, Travel Bugs, and kids stuff. It's on JC's Track which is a very pleasant walk between the rail and the river, going from the Otira Tunnel bridge to Rough Creek. You can find the track by going under the bridge either at the tunnel or under the bridge at Rough Creek. The Rough Creek end route is slightly shorter to the cache but I encourage you to walk the whole way, especially the river bank deviation. JC is a long time local who voluntarily established and maintains this track, including the many seats and paths.
You are standing on the old Cobb & Co. stagecoach road, used before the new main road on the other side of the rail tracks was built. There are several of the original buildings still around, placed here when it was still the main road. These include an tunneler's hut, and the original surveyor's cottage built in 1907. These are in private ownership, so please respect that.