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Sulphur Mountain Hike via Cosmic Ray Road in Banff

The boardwalk that takes you to the top of Sulphur Mountain
The boardwalk that takes you to the top of Sulphur Mountain
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Sulphur Mountain in Banff National Park, named for the sulphur odour emanating from the hot springs near the base of the mountain, is usually accessed via a quick and scenic ride on the Banff Gondola. That’s the easy way to get up and down the mountain. But there are two other options; do the Sulphur Mountain hike beneath the Banff Gondola or start at the Cave and Basin area, pick up the Cosmic Ray Road and end at the summit ridge boardwalk by Sanson Peak via Cosmic Ray Road.

Both hikes in theory can be done at any time of the year but the Cosmic Ray Road hike can be tough in winter if there is a lot of snow. Shoulder season – October to December and April to June are ideal for it. The hike beneath the Banff Gondola can be done year round – save if there is a big dump of snow.

The Cosmic Ray Road hike was closed for over a year but in April 2022 I saw that it had reopened – but that was online. On the summit ridge boardwalk it still says closed. Go figure. I’d suggest that you check the Banff National Park trail report info for updates. They call it the Sulphur Mountain Westside Trail – at least in winter.

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Sunset views from the boardwalk at Sulphur Mou
Sunset views from the boardwalk at Sulphur Mountain in summer

Sulphur Mountain hike via Cosmic Ray Road details

Length: 17 km return

Elevation gain: 880 metres (2887 feet)

Trailhead elevation: 1390 metres 

Time needed: 5.5 – 7 hours 

Difficulty: Moderate

Dogs allowed: Yes on a leash

Map Needed: Gem Trek Banff Up-Close

Sulphur Mountain hike from the Cave and Basin Trailhead

John and I did the Sulphur Mountain hike via Cosmic Ray Road in November when there was snow on the ground. We took snowshoes with us because we weren’t sure about the conditions, but as it turned out, we never used them.

The Sulphur Mountain hike starts off on a flat trail parallel to the Bow River. It’s the same approach you would use if you were going to cross-country ski or snowshoe into Sundance Lodge.

Although the signage at the start of the trail doesn’t include Sulphur Mountain, don’t let that worry you. You’re going to head towards Sundance Canyon but you won’t go that far. Instead look for a junction, 2.7 km and about 40 minutes into the hike. From the sign you’ll find here, you have 5.8 km on the Cosmic Ray Road to go to reach the Sanson Peak summit and it’s all uphill.

Follow the Cosmic Ray Road for its entire length. It starts off in the trees, but once you break out into the open, about 30 minutes after turning onto the road, you’ve got views for the rest of the hike. That’s a big reason the hike is so worthwhile. 

There’s no chance of getting lost once you’re on the road. Just keep walking, though I have to say at times the road felt like it would never end. When you make the first switchback – most of the way up – you’ve got about 30 minutes left of hiking to reach the boardwalk to the Banff Gondola.

Start at the Cave and Basin area even though the trail and mileage doesn't show on the sign
Start at the Cave and Basin area even though the trail and mileage doesn’t show on the sign
Look for dippers (a black bird) in the quiet pools as you hike parallel to the Bow River
Look for dippers (a black bird) in the quiet pools as you hike parallel to the Bow River
Pretty forest walking in Banff National Park
Pretty forest walking
Head for Sulphur Mountain and Sanson Peak via the Cosmic Ray Road
Head for Sulphur Mountain and Sanson Peak via the Cosmic Ray Road; that intersection is before Sundance Canyon
It's a steady 880 metre climb to the top at a pretty constant grade
It’s a steady 880 m climb to the top at a pretty constant grade
 The first good lookout from the Cosmic Ray Road
The first good lookout on the Sulphur Mountain hike via the Cosmic Ray Road
Looking back to Mt. Louis
Looking back to Mt. Louis
Stopping to admire the view on the Cosmic Ray Road
Stopping to admire the view
 Almost at the first switchback
Almost at the first switchback

Sanson Peak via the boardwalks

John and I didn’t see a soul on the trail from the minute we left the parking lot until we reached the boardwalk. In summer, the top of Sanson Peak can be packed but it was cold and windy in November so there weren’t that many people that had ventured from the Banff Gondola building.

I highly recommend hiking to the top of the boardwalk to get the view from 2270 m Sanson Peak. It’s also the site of a historic meteorological station called the Sulphur Mountain Cosmic Ray Station National Historic Site. Mountain views up and down the valley from here are fabulous. 

If you’re frozen there’s the option of heading to the gondola building to warm up and perhaps even have something to eat. Although you could take the gondola down – for a price – it can be time-consuming to get back to the Cave and Basin parking lot unless you’ve taken two cars and done a shuttle.

Cosmic Ray Road history

There’s an interesting history to the Cosmic Ray Road – which sounds like something out of a sci-fi book. The road was constructed to help with cosmic ray research back in 1956 – one of nine such sites in Canada.

Research was conducted by the University of Alberta in Calgary from 1960 -1978. Signs along the boardwalk describe cosmic rays as “energized particles traveling at close to the speed of light after being accelerated by our sun or exploding stars in distant galaxies.” They are believed to be the cause of the Northern Lights.

The boardwalk that takes you to the top of Sanson Peak
The boardwalk that takes you to the top of Sanson Peak
You can see Lake Minnewanka from Sulphur Mountain
You can see Lake Minnewanka from Sulphur Mountain
Views looking west from the top of Sanson Peak are superb
Views looking west from the top of Sanson Peak are superb
The Sulphur Mountain Cosmic Ray Station National Historic Site
The Sulphur Mountain Cosmic Ray Station National Historic Site

The descent on the Sulphur Mountain hike via Cosmic Ray Road

It was a quick descent as the snow was just the right depth for quick stepping down the mountain. In two hours we were back at the car. All told we hiked 16.2 km over five hours – though I’d plan on six hours or more as we were really moving to stay warm.

On a November day there's aren't many people that have ventured from the gondola
On a November day there’s aren’t many people that have ventured from the gondola
It's quick walking down the snow
It’s quick walking down the snow – and we’re back at the car in two hours

For a fall or spring outing I don’t think you can beat the Sulphur Mountain hike via Cosmic Ray Road; great views, a good workout and the sense until you reach the boardwalk that you have Banff National Park to yourself. It all adds up to #anotherbestday in the mountains.

Where to stay in Banff

If you want to spend a night or two before or after the hike there are lots of great options.

One of my favourite places to stay is the Moose Hotel – just a short walk away from the Banff strip. Canalta Lodge is ideal for families and is known for its great price points. 

Buffalo Mountain Lodge with its lovely outdoor hot tub is a short drive out of town. 

The Fox Hotel and Suites with its cave-inspired hot pool is a favourite of many. 

For a boutique motel experience (new in 2022) with simple accommodation, check out The Dorothy Motel

More Banff National Park adventures you might enjoy 

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Sulphur Mountain hike via Cosmic Ray Road in Banff National Park

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