5.4 kilometres return, grade 3 on the scale WA Dept. of Biodiversity, Conservation and Attractions uses for its walk trails, and about two and a half hours if you stop properly at the pools rather than just glancing at them from the track. That's the number I wrote on the back of my hand before we started, in biro, because I'd left the notebook in the car. It turned out to be about right, give or take the fifteen minutes we lost when my partner decided a granite ledge above the main pool was a reasonable place to eat a sandwich.
The Serpentine Falls walk gets talked about as an easy afternoon out from Perth, and in fairness the distance backs that up. What the distance doesn't tell you is how much of it is exposed granite, and how differently that behaves in July compared to February. I've done this one in both seasons now, and they're not really the same walk wearing different weather.
The numbers before the view
Start at the day-use car park off the falls access road, follow the marked loop down past the old flour mill ruins, and you're at the base of the falls inside twenty minutes if you don't dawdle. Most people do dawdle, and that's fine — the mill site is worth the few minutes it costs you, and there's shade there that you won't find again until you're back near the picnic ground.
The grade 3 rating sits below anything serious on the Bibbulmun Track, comparable to a gentle stretch somewhere south of Dwellingup rather than the rockier sections further down toward Pemberton. I use the Bibbulmun as my yardstick for most day walks in this state because it's the one measuring stick that doesn't move, and against that stick this one is a warm-up, not a test.
Getting there, and paying the fee
The park sits off the South Western Highway, with the turn onto Falls Road clearly signed if you're coming from Mundijong direction. There's a per-vehicle entry fee payable at the honesty station or online in advance, standard practice for a park managed under the Biodiversity Conservation Act 2016, and it goes toward the maintenance that keeps the granite terraces from washing out every wet season. I mention the fee because I've watched more than one visitor grumble about it at the gate as though it's a surprise. It's on every piece of signage for a hundred metres before you get there.
Parking fills early on weekends, particularly through spring when the falls are running properly. If you're planning to beat the crowd, or you just don't fancy the drive out before dawn, there's a solid write-up on camping near Serpentine National Park for an early walk start that covers the closer options. I did exactly that the second time round, tent pitched twenty minutes out, boots on the track before the first car park attendant had turned up.
What's actually underfoot
The granite is the whole story here, and it's the part the brochure photos don't show you. Dry, it's grippy and forgiving, the kind of surface you can walk fast on without thinking about your feet. Wet — and this is a waterfall walk, so wet is not a hypothetical — it turns to something closer to wet tile. I wore my usual merino hiking socks and left the gaiters in the car, which was the right call in February but would have been the wrong one in August when the lower sections near the pools get a fine mist off the falls that keeps the rock permanently damp.
There's one short scramble section near the second lookout where the track narrows and drops away to your right. Nothing that needs a harness, but I did see a kid in thongs nearly go over sideways there, and his mother's face told me she hadn't expected that section to exist.
The pools everyone posts, and the one they skip
Here's my one genuine gripe with how this walk gets described. The DBCA family-friendly tag on the signage is generous, and I'd argue it undersells the risk on that lower granite in the wet months rather than the distance or the gradient, which are both genuinely easy. Families with younger kids do this walk constantly and mostly fine, but