The corridor’s quietest swim is hidden in second-growth forest, six rolling kilometres above Howe Sound — and most people drive right past it.
The traditional start crosses Highway 99 near Murrin Provincial Park, and access at this trailhead has been subject to change over the years. Verify the current trailhead status and parking rules before you go, be extremely careful anywhere near the highway — traffic is fast and sightlines are short — and know that the Murrin lot fills early on summer weekends.
Petgill is the hike for people who think they’ve done everything between Vancouver and Whistler. It starts near Murrin Provincial Park, climbs into mossy second-growth, breaks out onto bluffs over Howe Sound, and ends at a lake warm enough for real swimming.
That last part deserves emphasis. Most water in this corridor is glacial, and “swimmable” usually means “survivable for ninety seconds.” Petgill is different — a shallow, forest-ringed bowl that soaks up summer heat until, by mid-July, you can float around among the lily pads without a countdown running in your head. Brohm Lake north of town is the other famous warm one; Petgill is the one you earn on foot, which is exactly why it stays quiet.
Budget more time than the stats suggest. The trail rolls constantly — short climbs, short drops, repeat — and the 11-odd kilometres feel longer than they read.
Somewhere in the first kilometre you stop hearing the highway, and that’s when Petgill starts. The forest here is second-growth — big stumps from the old logging days, new trees crowding up between them — and the moss has taken everything it can reach: logs, boulders, the edges of the trail itself. On a wet morning the whole understorey glows green. On a hot afternoon it smells like sun on fir needles, which is its own argument for coming.
The trail’s defining habit is that it will not commit to going up. It climbs, drops, sidehills, climbs again. On paper the cumulative gain is on the order of six hundred metres; on your legs it feels like more, because you pay for some of it twice — once on the way in and again on the way out, when the “descent” keeps finding new rises to throw at you. Nobody warns first-timers about the return leg. Consider yourself warned.
The reward for all that indecision comes partway in, when the forest thins and the trail steps out onto open granite. These bluff viewpoints are the best moments of the hike — sudden windows over Howe Sound, with the water a long way down and the islands laid out like a raised-relief map. They also make natural pacing marks, so we’ve numbered them below the way we count them in our own field notes.
Bring more water than a 12 km day usually asks for. The rolling profile works you harder than the number implies, and there’s nothing to refill from that you’d want to drink untreated.
Early in the climb the trees open for your first clean look at Howe Sound. It arrives sooner than you expect and it’s a good calibration point: if the party is struggling here, the rolling middle section will not improve their mood. If everyone’s grinning, carry on.
The most generous of the viewpoints — room to sit, sun on the rock, and the Sound spread out below with the ferries drawing slow white lines across it. Most groups break here in at least one direction. Stay back from the lip; the moss that makes these bluffs beautiful is also slick when damp, and the edges are unforgiving.
By now you’re well into the rolling middle stretch and the views come briefer — a gap in the canopy, a shoulder of rock, the water flashing blue-grey through the trees. This one exists mostly to remind you why you’re up here, right around the point where the ups and downs start feeling personal.
The final window is the one you walked in for: the trees part and Petgill Lake sits there, small and dark-green and completely indifferent to the effort involved. No crowd noise, no parking lot hum. Usually just dragonflies, lily pads, and — if you’ve timed it right — nobody else.
Petgill’s party trick is temperature. By mid-summer the lake is warm enough for actual, unhurried swimming — a rarity in a corridor where most lakes run glacier-cold all year. Lily pads crowd the quiet margins, and half-sunken logs around the shore serve as diving platforms, sun decks, and lunch benches, depending on your ambitions. On a weekday you can have the entire place to yourself for an hour at a stretch.
Swim sensibly: it’s a remote lake with no lifeguard and no easy way out if something goes wrong. Ease in, check for submerged wood before any enthusiastic entries, and keep an eye on anyone in your group who runs cold.
There are no facilities of any kind at the lake — no outhouse, no bins, no signage to clean up after you. Everything you carry in comes back out, including orange peels, apple cores, and whatever your dog produces. The lake stays lovely because the people who make the effort to walk in have, so far, mostly respected it. Be part of the “mostly.”
Give yourself real time up here. The most common Petgill regret isn’t the rolling trail — it’s hikers who spend three hours walking in, ten minutes at the water, and three hours walking out. An hour at the lake is the minimum sensible dose.
“Every other lake this close to the highway makes you share it. Petgill makes you earn it — and then it’s yours.”
| Months | What you get | Verdict |
|---|---|---|
| Nov – Mar | Short days, wet moss, and possible snow on the upper trail. The bluffs can be beautiful in clear cold weather, but check current conditions and turn around early — this is no place to finish in the dark. | Experienced only |
| Apr – May | The forest at its greenest and the trail at its muddiest. Lake still cold. Quietest season of all — you may not see another person. | For the moss |
| June | Trail dries out, days stretch long, and the lake starts its slow climb toward swimmable. Brave people swim; sensible people wait a few weeks. | Warming up |
| Jul – Aug | Prime time. Warm water, sunny bluffs, dragonflies. The catch is at the bottom: Murrin’s parking fills early on summer weekends, so arrive at breakfast hour or come midweek. | The swim window |
| Sep – Oct | The locals’ pick. Water holds some warmth into early September, crowds vanish, and the low autumn light on the Sound from the bluffs is the best of the year. | Golden hour |
First, the stats lie by omission. Eleven-ish kilometres and six hundred-ish metres sounds moderate, but the constant rolling means it hikes bigger than it reads. Fit hikers do it comfortably; anyone expecting a flat forest stroll to a swim hole will be filing complaints by the halfway mark.
Second, the start is the sketchiest part of the day, and not because of the terrain. The traditional approach involves crossing Highway 99, where traffic moves fast and drivers aren’t looking for pedestrians. Access arrangements at this trailhead have changed before and could change again — check the current trailhead status and parking rules before you commit, and treat the highway with more respect than anything on the trail.
Third, the views are intermittent, not constant. Between the numbered bluffs you’re in the trees, and if you need a summit panorama to feel a hike was worth it, this isn’t your day. Petgill’s pleasures are quieter: moss, birdsong, warm water, and the particular smugness of swimming in a lake most highway traffic doesn’t know exists.
Last: no facilities means no facilities. Deal with everything accordingly, and pack out every scrap.
Petgill needs boots, water, and an early start — no boat required. If you want gear support for a Sea to Sky day (canoes and boards for the lakes you can paddle, before or after this hike — delivered to the water, or picked up and dropped off at their Squamish base if you’d rather haul your own), the local outfit we trust runs everything through Rented Local.
And if you come off the trail by early afternoon with energy to spare, the classic double-header is an afternoon of water sports back in Squamish — Squamish Canoe Rental puts canoes (up to three paddlers each) on calm water fifteen minutes up the highway, and the corridor water guide covers the rest of the options. The same crew also runs Squamish Water Taxi — jet-boat crossings on the Squamish River and Howe Sound tours — when your trip needs the far side of a river. Warm-lake swim, bluff views, and an evening paddle: that’s a complete Sea to Sky day.
Roughly 11–12 km round trip with on the order of 600 m of cumulative elevation gain, spread across constant rolling ups and downs. Most parties take 4–6 hours car to car, plus however long you spend at the lake — and you should spend a while.
Yes — and unusually for the Sea to Sky corridor, it’s genuinely warm by mid-summer, not just tolerable. It’s a shallow forest lake that soaks up heat through July and August. There are lily pads, logs to sun on, and no lifeguard, so swim with the usual backcountry caution.
The traditional start is near Murrin Provincial Park on Highway 99, south of Squamish near Britannia Beach, and involves crossing the highway. Access and trailhead arrangements here have been subject to change, so verify the current trailhead status and parking rules before you go, be extremely careful near the highway, and note that Murrin’s lot fills early on summer weekends.
Moderate, but sneaky. No single climb is long, yet the trail rolls the whole way, so the cumulative effort is bigger than the stats suggest — especially on the return leg, which keeps finding small rises when you think you’re done. Reasonably fit hikers manage it comfortably with enough water and snacks.
None at all — no outhouse, no garbage bins, no services of any kind. Pack out absolutely everything you carry in, including food scraps.
Dogs do this trail regularly, but check current signage and rules at the trailhead before you go, keep your dog under close control near the highway crossing and the bluff edges, and pack out after them. Carry water for the dog too — the rolling trail works them as hard as it works you.
Mid-July through August for the warm-water swimming, on a weekday if you can manage it. September is the connoisseur’s pick: the lake holds some warmth early in the month, the crowds are gone, and the autumn light over Howe Sound from the bluffs is the best of the year.
Don’t count on it. Coverage in the forest above the highway is patchy at best, so download any maps before you leave, tell someone your plan, and treat the hike as self-supported.