Summary: Under the Motorway is an interesting bushwalking that goes from an idyllic natural pool in Cockle Creek to a graffiti-covered underpass that crosses the F3 motorway. 

What I’ve called the “Under the Motorway” bushwalk ends up being quite a fascinating and somewhat unexpected walk – and not what I had planned! The plan was to start on the fairly popular Gibberagong Track in North Wahroonga, and then immediately turn onto a side-trail which heads north to join up with the Chase Trail. Initially, I’m on track, so to speak: the bushwalking track is easy to follow and matches the track which is shown on my map.

Someone has conveniently chalked a couple of entirely unnecessary arrows on the rocks, and some equally redundant white ribbons are occasionally seen hanging from trees.

After about 600m, the track drops down through some large boulders, guarded by a brush-turkey or gweela. (We have multiple brush-turkeys in our garden at home, but it’s the first time in a while I’ve seen them while bushwalking.)

The track changes from dense heath to more open grassland with tall eucalyptus trees as it descends. The track is still where may map says it should be – although after 800m there is a junction with another track that heads south, marked by white ribbons. I follow this a while but it quickly peters out after reaching a small stream.

The main track continues to descend, and suddenly I emerge from the bush to find myself in front of a deep pool and a series of cascades through moss-covered rocks. I’ve reached Cockle Creek, which a bit further downstream meets the Gibberagong Track. It’s an idyllic, serene and somewhat unexpected spot.


The track crosses Cockle Creek and ascends the other side of the valley. Low grasses are soon replaced by a forest of tall trees with almost no undergrowth. The path is generally still easy to follow; but when I get to the location where the junction with the Chase Trail should be, I can’t find it. There’s no sign of any trail heading to the north. But the trail does continue to the east, towards the F3 or Pacific motorway.

I decide I’ll follow the trail, thinking it will lead to a cutting overlooking the motorway. It’s actually one of the nicest parts of the walk, crossing another stream and passing through tall eucalypt forest.


Beyond the sea of ferns is a small sandstone cliff, which I briefly explore thinking there may be some Aboriginal engravings on the top (I couldn’t find any).

A little further on, where the track stops on my map, there’s some interesting rock formations. Huge sandstone boulders lie at all sorts of angles; they appear natural but perhaps result from excavations or explosives used in constructing the F3 motorway, 35 years ago…

The track continues past these rock formations, crossing an obviously man-made drainage channel before a graffiti-covered tunnel comes into view.

The track continues down to the wide entrance of the tunnel, which has a trickle of water down the middle. It’s slightly surreal having just walked through a forest of gum trees and ferns, to now be in the middle of a concrete tunnel under a six-lane freeway.


On the other side of the tunnel, the creek is fringed by lillies and ferns.


To add to the surrealness of the walk, as I’m having a look around the creek, I almost walk into an enormous bug in a tree… I realise after my initial surprise that it’s a geocache. From the cache description, it’s possible to reach this side of the tunnel from the Chelmsford Fire Trail – but I can’t see any obvious track.


I return the same way – even if I did find Chelmsford Fire Trail that goes up to Chelmsford Road in Asquith, there wouldn’t really be any viable way to get back to the car (as I’d be on the wrong side of the motorway).

On the way back, I stop again at the Cockle Creek pool; I can’t resist taking another break here – and taking a few more photos.


The trip back from here is pretty quick, with the trail ascending to the Gibberagong Track. Definitely an interesting walk – and not what I was expecting!

0.0km Start of Gibberagong Track
0.2km Take unnamed track of Gibberagong Track
0.8km Junction with track heading south / left (ignore this)
1.1km Cockle Creek
1.7km Junction with Chase Trail should be here (couldn't find it)
2.5km F4 motorway underpass
2.7km Opposite side of freeway
4.6km Cockle Creek
6.0km Start/End of Gibberagong Track

For more bushwalks (as well as swimming spots and other activities) visit the Guide to Ku-ring-gai Chase National Park.

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Yvonne Everett · May 2, 2020 at 10:05 pm

Lol, we made the same error heading towards the freeway instead of Chase Trail. I’ll email you my GPX which shows our route after we retracked and picked up the right path. The GPX also has the Pipeline Track on it, which is fun to explore. I call the Pipeline Track the Narnia Route, because you have to walk across the picnic table to access it (not quite a cupboard, but the same secret entry feel).

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