Follow Lyons Rd some 5.5km to SH2, turning right (W) onto Mangatawhiri Rd for the last 500m to SH2.
Keep well off the road shoulder on Mangatawhiri Rd and SH2 as these are extremely busy roads with a lot of traffic.
Head down the side of SH2 (no need to cross it) and cross a stile to take you under the bridge and onto the stopbank route.
Mangatawhiri River Track - 6.5km / 2hr
This track opens up a little-seen corner of New Zealand where you'll overlook from the stopbank, Dutch Polder-style agriculture. It follows the Mangatawhiri River from the SH2 bridge south-west to the exit at McIntyre Road.
Day trippers beware: SH2 is a fast highway. It is best to drive across the bridge and pull off the highway onto Mangatawhiri Rd, then make your way back on foot, below the road-bridge.
Follow the stopbank which is on the true left of the Mangatawhiri River – i.e. the left bank as you face downstream. There’s one low-lying area about halfway along which may flood, but only in very wet weather. After a 5km walk down the stopbank you’ll come to a drainage ditch about 10m wide. At this point the stopbank, and the track route, turns a right angle and follows the drainage ditch inland for about 1km before finishing at the McIntyre Road end, and a pump-station there for an Archimedes Screw which is part of the drainage.
If you want to see what this land was like before being modified, look across the drainage ditch and you'll see land run by the Auckland/Waikato Chapter of Fish and Game. It's natural swamp.
Mercer - 4.5km / 1.5hr
McIntyre Road is a little used road serving only a few houses. It has views across the Fish and Game swampland, and a relaxing shady section before it reaches the junction with Kellyville Road.
Note: after heavy rain and when the river is running high, this route may be under water - check conditions carefully and if water is high, use the Koheroa Bypass as an alternative.
After crossing the railway line follow the markers into the trees opposite and under the Southern Motorway bridge.
Turn left/south and follow the marked route parallel to the motorway 1.5km to the Mercer Service Centre - where a petrol station, cafe and foodcourt are available for refreshements before you leave the Auckland region and enter Waikato.