The coordinates given are safe place to park your cark. From there make your way over the green gate and down the concrete path, find Waypoint 1 to start your exploration of the Ngaio Gorge. The trip will take you up stream along a formed track, this may be wet and boggy in parts so suitable footwear is advised. The first two waypoints will provide the coordinates to make your way to Waypoint three, you will need pen and paper to record this information. At the third Waypoint you will need to find a small container that holds pieces of paper you can take, with the final coordinates and a clue (in ROT 13) to held find the final.
The final cache is a 200ml sistema clip top container with a logbook and pencil.
GPS coverage is marginal due to terrain and topography, at the time of setting up the best accuracy obtained was +/- 10 metres, so you will have to use your powers of observation and the clues given at each waypoint to help find your next goal.
Update 14 January 2021
Due to the slip remediation work that is being carried out at present on the Ngaio Gorge road, access and parking at the given starting point will be not possible on some occasions. This is expected to be the situation until October 2022. There are other trail heads that can be used, such as from the bottom of Hanover Street in Wadestown, or my recommended alternative in Trelissick Crescent at S41° 15.404 E174° 46.206 which has better parking. Starting and finishing from either of these points will not involve much more walking compared to the Ngaio Gorge coordinates but does mean a bit more climbing is required.