Porters Pass Secret Rock Pool, Blackheath: Centennial Glen Canyon Swim

Halfway around Blackheath's Porters Pass Circuit, up a side track signposted 'canyon', there's a small, deep rock pool hidden inside a slot canyon at Centennial Glen, fed by its own cold waterfall. It's shaded, quiet and easy to walk straight past if you don't know it's there.

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The circuit itself is one of the upper Blue Mountains' most varied walks, linking Colliers Causeway with Centennial Glen through rainforest gullies, past weeping rock walls and along narrow cliff-side ledges, with far fewer people than the big lookouts. We cover the full route in Swim New South Wales; here's a taste of what to expect.

Swimming at the Porters Pass Secret Rock Pool

The pool sits at the bottom of a narrow slot canyon carved into soft sandstone by running water. To reach it you walk a short way along a rock ledge under an overhang, then climb down one large boulder to the water's edge. It's an awkward step, so take your time.

The plunge pool is surprisingly deep for its size and fully shaded by the canyon walls, with a cold waterfall pouring in. Even on a sweltering summer day, expect a sharp, icy dip rather than a long swim. It's small, so it's best enjoyed by one small group at a time.

The canyon stays damp year-round, and the walls are covered in mosses, ferns and weeping-rock plants. Because the pool is a closed, sensitive system, skip sunscreen and insect repellent before you get in, stay on the stone paths and steps to stop erosion, and carry out every scrap of rubbish.

Go on a hot, dry day after a run of fine weather. After heavy rain the canyon is no place to be.

How to Get to the Porters Pass Secret Rock Pool

Blackheath is roughly 1 hour 45 minutes from Sydney along the Great Western Highway. Our guide starts the circuit from the signposted trailhead at Burton Road on Blackheath's residential western side, where there's free street parking on the grassy verge but no formal car park or facilities. Some walkers start from the Centennial Glen car park instead.

We recommend walking the loop anti-clockwise: follow signs for Porters Pass, then Colliers Causeway, to reach Centennial Glen. After about three kilometres of rough, uneven track, rock-hop across the creek into the glen and climb the stone steps to a small junction. The side track marked 'canyon' leads to the pool. To finish, follow signs for the Centennial Glen exit and Fort Rock back uphill to the start.

The full circuit is a little over 5 km. Allow 2.5 to 3 hours plus swimming time; walking anti-clockwise, you'll reach the pool after roughly 1.5 hours.

Know Before You Go

• The track is rough, with steep rock staircases and narrow ledges. Not suitable for young children or unsteady walkers.
• Wear grippy shoes that can get wet. Rock in the canyon is slippery throughout.
• Never jump or dive into the pool. It's small, there are rocks around the edges and there are no lifeguards.
• Avoid the canyon after heavy rain. Flash flooding and strong flows are real risks.
• No mobile reception in the canyon sections. Tell someone your plans.
• Watch for leeches, snakes and sharp rocks in the damp canyon.
• Keep the water clean: no sunscreen or repellent before swimming, stay on stone paths and carry out all rubbish.
• Check track conditions with the land manager before you go, as closures can happen after storms or rockfalls.

Porters Pass Secret Rock Pool FAQs

Where is the secret rock pool at Porters Pass?

It's in a small slot canyon at Centennial Glen, Blackheath, reached by a short side track signposted 'canyon' off the Porters Pass Circuit.

How long is the Porters Pass Circuit?

A little over 5 km. Allow 2.5 to 3 hours to walk it, plus time to swim.

Which way should you walk the circuit?

Anti-clockwise is the most scenic way in: Porters Pass, then Colliers Causeway, then Centennial Glen, reaching the pool after about 1.5 hours.

Is the water cold?

Very. The pool is fully shaded and fed by a waterfall, so expect an icy dip even in summer.

More Blue Mountains Swims & Gems

• Dalpura Canyon: another hidden canyon swim near Blackheath.
• Pool of Diana: an emerald waterfall pool with a sandy beach on the Newnes Plateau.
• Casino Dome, Hydro Majestic: the clifftop hotel's landmark dome, just down the highway at Medlow Bath.
• Blue Mountains Swimming Guide: our roundup of the region's best waterfalls and swimming holes.