Hihi Grunter

This is a hill and back run (not hilly just 1 long hill). Start at the carpark and head along the track a few hundred metres till you cross a small bridge. Immediately after this turn right on the Main Ridge Track (also one end of the water race track). From here every right hand option is your friend (avoid the left options today, they are undulating nice easy tracks for your recovery tomorrow).

Keep on the main ridge track up to a small lookout diversion you'll see on your left near the top of the first climb (its worth the look). After this small diversion back on the track you will be lulled into a false sense of security on a fun downhill that is short lived and meets the junction to Collins Drive West (ignore this for the moment) and keep on the Main Ridge Track to Hihi and Paton Stream Dam, which is of course up, up and up. If in doubt head up.

After the next climb you'll see the Paton Stream Dam track junction on your right (again that's for later) right now you're focussed on burning the quads so keep going up. You'll find this section gets into super pretty bush (moss, small streams unless its the peak of summer) and nice cover overhead. Follow this all the way to Hihi which has a short antenna station on it - admire the views, take a selfie of your bright red sweaty face and if you've been puffing like a steam train reflect on the fact you just climbed from 30m above sea level to 730m. In about 5km.
Head on down back where you came from - now the fun begins. On your way down take the Paton Stream Dam turn off and you'll find the remnants of an old Kauri slip dam (see pics). This is a cool spot where you feel like the only person on earth among big old kauri square cut beams strewn across the stream valley (see pic). Follow your steps back to the main track turn left and head on down to the junction you passed earlier today with the track to the Collins Drive West entrance. Flick your headtorch on and check out this 600m tunnel shaft that was blasted and pick axed in vain in the hope of a quartz reef full of gold. Nice work fellas, you made a cool diversion for this run, bummer about the lack of gold though.

Head through the tunnel and at the other end take the track down to water race track and turn left to head back towards the carpark. Form here any of the tracks will eventually take you near the river which you can follow back to the carpark. If you turn right it just adds a km or two (the Battery Hills recreational area map is a handy way to explore round here - there's a few more shafts and tunnels about and some great swimming holes on the Puketui river to soak those legs in)