Nine ancient volcanoes line up between San Luis Obispo and the sea, and the tallest one is a 3.5-mile hike
Most people blast through San Luis Obispo on Highway 101 without realizing they just drove past a row of ancient volcanoes. There are nine of them, lined up like stepping stones for about 17 miles from town to the ocean at Morro Bay.
The tallest is Bishop Peak, and its summit is a rocky, wind-scoured perch with the whole chain laid out below you. Here’s what the hike is like, and how to time it so the climb doesn’t cook you.
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How a line of volcanoes ended up in SLO
The Nine Sisters, also called the Morros, are volcanic plugs. Roughly 20 to 25 million years ago, magma pushed up beneath a layer of softer rock and cooled in place, and over time that softer rock wore away and left the hardened cores standing as lumpy, rugged peaks.
Morro Rock is the famous one, parked at the ocean end of the chain at 576 feet. Bishop Peak, at around 1,550 feet, is the tallest of the bunch.
Black Hill, another one of the sisters, has a short trail near Morro Bay that looks straight down onto Morro Rock. It’s a fun warm-up, but it won’t show you the whole lineup the way Bishop Peak does.
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What the Bishop Peak hike is actually like
From the Highland Drive trailhead, figure about 3.5 miles round trip with roughly 1,000 feet of climbing. Starting from Patricia Drive adds a bit more distance and a bit more elevation.
The first stretch is the gentle part: a wide dirt path under oaks and bay trees, shady and cool even on a bright day. Then the trees quit, and the trail switchbacks up an exposed, rocky slope through orange-tinged boulders and brush.
Is it hard? Depends who you ask. The trail is well used and easy to follow, but the upper section has almost no shade, and getting onto the summit rocks takes some light scrambling with both hands free.
Up top, the view does the bragging for you: downtown SLO, Cal Poly, Laguna Lake, and Cerro San Luis across the valley. Look west and the rest of the Morros march off toward Morro Bay, one bump after another.
This is the single best way to understand the Nine Sisters. From the highway they look like random hills, and from up here the line is impossible to miss.
The very highest boulders take real technical climbing, so most hikers stop at the rocks around the summit benches and call it a win. Nobody’s checking.
This volcano still has a day job
Bishop Peak isn’t just scenery. Quarrying on its flanks goes back to around 1890, and stone from the area once went into the breakwater at Avila Beach.
A quarry on neighboring Madonna Ranch land still fires up now and then. Its rock helped with repairs after the 2017 Mud Creek Slide on Highway 1, and in 2024 it supplied stone for a Caltrans fix at Big Sur Lookout.
So the next time you cruise the Big Sur coast, you might be rolling over a little piece of this volcano. Not a bad bit of trivia for the summit.
When to go and what to know
SLO’s inland valleys can stay warm well into fall, and the top two-thirds of this trail sit in full sun. Start early, carry more water than you think you need, and save the afternoon for wandering downtown.
If you’d rather wait, winter and early spring bring cooler temps and green hillsides. Weekends get busy and parking at both trailheads is along the street, so a weekday morning is the easy win.
The trail sits inside Bishop Peak Natural Reserve, part of the City of San Luis Obispo’s open space. It closes from one hour after sunset until one hour before sunrise, dogs need to be leashed, and it’s hiking only, with no bikes and travel limited to designated trails.
Still have gas in the tank? Cerro San Luis, the sister right across the valley, has its own summit trail, and our roundup of hikes in San Luis Obispo covers it along with a few shorter climbs. For the rest of your weekend, here are the best things to do in San Luis Obispo and things to do in Morro Bay at the ocean end of the chain.
So, how many of the Nine Sisters have you knocked off? Tell us which one you’d climb next, and whether Bishop Peak lives up to the hype.
Trip tips: grab a rental car to get out here, lock in your hotel before the good rooms are gone, or skip both and book a camper van instead.
Rules and fees change, so always confirm current requirements before you go.
