If you're going to Whitireia Park by car then you'll be entering by this road. If you're on foot this is just one of many entrances. The cache is by the gate entrance which is closed overnight. Occasional cars might go past but the low speed limit gives you plenty of warning. Avoid parking next to the cache for a park and grab since the road is narrow - please park either at the bottom of the hill where the road is wider (150m) or at the top (400m). There is a driveway just opposite the cache - use discretion.
The cache is small black plastic container with 4 clips. Make sure you seal them all when returning the cache to keep the moisture out. It is intended to be a straightforward find so you don't have loiter here.
If you plan on driving into the park (and why wouldn't you having got this far?) please note that the gate is nominally closed at 6pm in the winter and 9pm in the summer. Not sure when the switch occurs, presumably at the daylight saving change. The sign at the entrance will tell you before you enter.