Summary: The Mullet Creek Tunnel (or more accurately, culvert) was built in 1889 as part of the Sydney to Newcastle railway line construction. The historic tunnel is reached via firetrails and a bushwalking track from the Mullet Creek Trail down to the creek.

I’ve seen a few social media posts about the Mullet Creek Tunnel – or more accurately the Mullet Creek Culvert – which was constructed in the 1880s as part of the main northern railway line between Sydney and Newcastle. It’s not particularly hard to find, but there’s not much information available on getting to this historic feature.

Much of the Mullet Creek Tunnel bushwalk is along firetrails, so unfortunately it’s not the most interesting walk until you get to the end. Starting from Woy Woy Road, you follow the Tunnel Track. The firetrail passes an old (flooded) quarry before reaching a major junction after 1.8km.

At the junction, turn right down the Mullet Creek Trail, another firetrail (turning left takes you to the Trough Waterfall and continuing straight ahead takes you to Rocky Ponds and the Icicles). You may see a few people on the trail, as it’s one of the ways you can reach Mount Wondabyne, and a short section of the firetrail forms part of the Great North Walk route between Girrakool and Patonga.

As the Mullet Creek Firetrail gradually descends, it gets a bit more shaded and the walking a bit more pleasant on a warm day.

I take a short detour along the way to look an Aboriginal rock art site, which has both stencils and paintings.

At the very end of Mullet Creek Trail, there is a view over the creek, a timber power pole… and no obvious track down to Mullet Creek! I head west, to the right of the pole, finding a route down to the left of a small cliff line.

While there is no longer a track, I’m definitely not the first person to walk here – there are a number of stone steps cut into the rock, most likely for access when the railway line was being built.

At the bottom, there’s a flat, informal camping area right next to Mullet Creek, with a discarded cooking pot that hasn’t been used for a few years! This (I believe) was the main camp at the head of Mullet Creek, used for construction workers, where a wharf was located.

Nearby and hidden by vegetation is the First Quarry, where sandstone was cut for use in the railway. It’s a bit tricky to find – once you’re at the open campsite next to Mullet Creek, you need to head north-east through some scrub until you see some small cliffs; the quarry is at the base of these.

image 2 Finding the historic Mullet Creek Tunnel in Brisbane Water

Next to it is the Second Quarry, which was used from 1887 and is thought to have provided the sandstone for the piers of the original Hawkesbury River railway bridge that was completed in 1889. The quarry at Wondabyne did not start until 1922, and provided the sandstone for the replacement Hawkesbury River railway bridge which was built from 1939 to 1946. While the original bridge was removed, the sandstone capped piers remains in place.

Although I’d considered following the edge of Mullet Creek up to the railway tunnel, the vegetation is pretty thick and the ground rather boggy in places, so I return to the Mullet Creek Trail. About 400m from the end of the firetrail there’s a wide service trail that goes a short distance down the ridge. Where this ends, look for a bushwalking track that initially heads a little to the left – don’t try and go directly down the ridge, which is quite steep.

Like the track at the very end of the Mullet Creek Trail, this must have also had some heavy usage in the past – there are a number of stone steps cut into the sandstone.

The trail descends at an angle down the ridge, avoiding the steepest sections, before making a sharp turn back towards the head of Mullet Creek.

Just before the end of the bushwalking is a a slightly overgrown section, and then a one metre drop down to the creek level.

Although I’d seen photos and knew what to expect, it’s still felt a little surreal to be standing in such as impressive and perfectly built structure that’s in the middle of the bush. The southern end of the Mullet Creek Tunnel opens up directly onto the creek.

While it’s commonly called the Mullet Creek Tunnel (and it is a tunnel), it’s technically a brick arch culvert that was built to drain Myron Brook under the railway and into Mullet Creek.

image 1 Finding the historic Mullet Creek Tunnel in Brisbane Water
Source: Lost in Time History blog

Unless you’re visiting right at high tide or there’s been heavy rain, you can walk through the Mullet Creek Tunnel to the other side, under the Sydney to Newcastle railway line. The culvert is just before the railway enters a tunnel between Mullet Creek and Woy Woy Creek, which was the longest railway tunnel in Australia at the time.

From here it’s back the same way via the Mullet Creek Firetrail and Tunnel Trail; if it’s warm day, cross the Tunnel Trail on the way back for a swim in the Trough Waterfall, or in the creek above the waterfall.

Getting to the Mullet Creek Tunnel

The bushwalk starts on Woy Woy Road with the signposted Tunnel Firetrail. It’s about 15min south of Gosford and an hour north of Sydney. There’s limited parking at the start of the trail, and more parking along the shoulder of Woy Woy Road. Almost all of the walk is on firetrails, with the last few hundred metres being on a rough bushwalking track.

More information on the Mullet Creek Tunnel

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