Colo River via Island Mountain: A tough but rewarding loop

It’s hard to resist a bushwalk down to the majestic Colo… although this demanding route from the Drip Rock Trail adds a touch of masochism in the form of relentless scrub (and a decent amount of elevation gain) to the spectacular scenery of the Wollemi.

Drip Rock Trail to The Island via Clews Cave

Led by Bernard, our hardy crew sets off from the Drip Rock Trail at 8:15am as we walk the last kilometre or so to the end of the trail.

From here the day begins in earnest as we head straight into the thick scrub along an unnamed ridge in a northerly direction. After another kilometre glimpses open through the foliage of ridges folding into the distance and valleys dropping away — before we swing east onto a second unnamed ridge.

The second unnamed ridge offers the first view of the Colo River cliffs, which hint at the scale of the Colo gorge.

As the ridge descends, four minor cliff lines slow our progress, each of them negotiated by a slot or short scramble.

Soon our first destination is in sight on the other side of the gully: Island Trig (now more commonly called Island Mountain, or just The Island).

We scramble down the last of the cliff-lines, to reach the bottom of the gully.

We soon locate Clews Cave, an overhang named after Major Hugh Powell Gough Clews (1890–1980) – widely known as “The Major” – and a distinguished British-born Australian military surveyor. Clews undertook the second survey of the Colo River in the 1930s (the first having been done by Frederick Robert D’Arcy in the early 1830s). He approached the area from Putty Road at New Yard, making his way along the main spur to the west towards the Colo River and installing three control points: Parr Spur, Parr West and Island. Presumably he found shelter in this rather unassuming cave.

It’s not much of a cave — and we don’t linger — because the real work is about to begin. We need to negotiate a route up through the intimidating cliffs which protect all sides of The Island.

A steep, scrubby climb brings us to the saddle at the north‑eastern corner of The Island.

Like the calm before the storm, it’s a very pleasant, open and scrub-free approach along the saddle.

The open saddle ends abruptly with a knife-like ridge of rock, which looks equally treacherous and impassable. There’s no obvious way up, but as we start weaving through the giant boulders and sandstone outcrops we find a viable route on the right (west) side.

Although it seemed improbable when looking up the spine of rock from the bottom, it’s a fairly climb with a few scrambles, but no exposure.

Before we know it, we emerge on top of the cliff, with sweeping views over the Colo Gorge and Parr West.

We’re still not at the very top of The Island yet, but the last few hundred metres to the top of The Island is relatively easy walking.

The true summit lies a few hundred metres further, and while the trig is long gone, the panorama — endless ridges radiating from the gorge — more than compensates. (It doesn’t really; I’m still disappointed in the absence of any Trig Remains!)

The Island to the Colo River (Pass 28)

The Island also marks the highest point of our loop bushwalk at 545m elevation: from here we have a descent of almost 500m to the Colo River along Brumby Pass, or Pass 28 as documented by Brian Corlis. Corlis described it as “an easy ridge”; a perhaps slightly generous description of the route.

It is 1,600 feet up to Island Trig; it is a steep rocky scramble for about 900 feet; and when the Mountain Holly ceased to plague us the Mountain Devils took over, to say nothing of such minor annoyances as Dillwynia and Prickly Moses: but the view was worth it, and it is only from such vantage points as this that any idea is really gained of the overall rugged nature of the Wollangambe Colo country.

The Sydney Bushwalker, October 1968

The scrub is initially not too thick, but involves a bit of route-finding as we navigate between large rock outcrops and minor cliff lines.

It’s surprisingly slow going, and after an hour the Colo River still seems a long way beneath us…

Towards the bottom, numerous cliff lines that need to be negotiated.

There’s lots of scrambling, more scrub and a few slots to be slithered down as make our way down the last bit of ridge.

Finally, we reach the majestic Colo River.

It’s hard to imagine a more perfect spot for lunch than a sandy beach on the Colo (made slightly less perfect by the knowledge of the 400m ascent still ahead back to the cars!)

Colo River to Drip Rock Trail (Pass 29)

We start the (shorter) return leg of Colo River loop after lunch, taking Cascade Pass (Pass 29 / 29a) which starts by following a creek up from the river. The rocky terrain is a welcome relief from the prickly scrub, with the risk of being poked in the eye now replaced by the danger of slipping on the moss-covered, slick rocks.

It’s one of the most picturesque sections of the walk, with the sun poking through the tall Coachwood trees and occasional emerald-green pools of water. (Some of the pools would be better described as stagnant, but they look emerald-green in the photos…)

We soon reach one of two obstacles on Pass 29, a 15m waterfall which was described to Bernard as being “exciting” and by the more restrained Colis as “requiring some meandering”. It does look a little daunting from the bottom, but a series of ledges provides a route up the left-hand side.

From the top of the waterfall, Pass 29 (and 29a) continues up the creek.

There’s lots of scrambling but nothing as “exciting” as our waterfall!

At the junction of two creeks Pass 29 and 29a diverge; Pass 29a is described by Corlis as being the easier of the two, and follows the right branch of the creek. We take Pass 29, which goes up the spur between the two creeks.

Unfortunately, leaving the creek means we are back in the Colo scrub. Pass 29 also involves negotiating what Corlis describes as “a number of cliff-lines” – and which Patrick in our group (after looking at the LIDAR map) defines more accurately using terms not appropriate for a family-friendly blog. We are all too soon at the base of the “mother-f&%ing cliff”, and while it looks somewhat daunting as we look up, it consists of a series of smaller cliffs.

After finding a way up the lowermost cliff, we sidle along the base of the cliff before finding another break where we can scramble up another level. (I’m not entirely sure if we are sidling along the cliff-line, or zig-zagging up the cliffs, or a combination of the two).

The next zig (or zag?) takes us to another spectacular weathered overhang with views of the distant Colo cliffs.

We are soon at the top of the cliffs, which turn out be far less challenging the LIDAR map suggests, and enjoy our last, quick break.

The ridge continues to ascend, but the last of the cliffs and any serious and/or exciting obstacles are now behind us.

In hindsight, we should have continued for another ten minutes, as we suddenly emerge onto a small rock platform that offers one of the best views of the day over the Colo. From here there is a great View of Island Mountain (on the far right) which looks a lot less intimidating from here, and the long ridge we took down to the Colo. To the west, the ridges between the Wollangambe and Clews Ridge roll away in layers.

It’s mostly pleasant walking as we continue along the ridge, with the scrub fairly thin most of the way.

A final vantage point provides a view back towards the Colo River and the distinctive Island Mountain in the middle, with Parr West on the right.

Another 15min of scrub-bashing gets us back onto Drip Rock Trail for a very short walk back to where we left our cars.

We reach the cars at 5pm, just before it starts to get dark: the Drip Rock Trail to Colo loop via Island Mountain took us just under nine hours, with minimal breaks. Previous trip reports suggest a slightly faster time – the intensity of the scrub (which is fairly thick along most of the ridges – has a fairly significant impact on the overall pace.

Getting to the Drip Rock Trail to Colo trailhead (Pass 28 and 29)

The loop bushwalk starts along the Drip Rock Trail, which is off Putty Road 5.5km (5min drive) north of the Ampol Colo Heights service station. Drive about 11.4km (25min) along the Drip Rock Trail where there is space to park on the shoulder; the last kilometre of the firetrail gets very rough even for a 4WD (while most of the unsealed Drip Rock Trail is suitable for an AWD/SUV, a 4WD with low range is highly recommended for the very steep section near the start.)

More information

• SBW Magazine & History Project – October 1968 [Wollangambe Wanderings]
• Noel R Gough – “The Major”: Lt. Col. Hugh Powell Gough Clews [PDF]
• Brian Corlis – Colo River Passes and Routes [PDF]