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United States
California
Marin County

Camino Alto Open Space Preserve

The best gravel rides in Camino Alto Open Space Preserve

By Fede from komoot

ยท

Updated June 4, 2026

If you've ever tried planning a gravel biking trip to Camino Alto Open Space Preserve, you know the feeling: a quick search reveals a dizzying array of options, making it tough to figure out which routes are genuinely worth your time and effort. It's easy to get lost in the sheer volume of trails, wondering which ones offer the best views or the most satisfying challenge. That's exactly why we're here to cut through the noise.

Our komoot community has ridden, mapped, and reviewed these trails, so consider this your curated shortcut to the best gravel biking in Camino Alto Open Space Preserve. We've sifted through the data to bring you a selection of routes that truly deliver, saving you the guesswork and ensuring your legs are spent on trails that matter. You'll find everything from wide fire roads to more technical single tracks, all set against a backdrop of diverse ecosystems, from grasslands to dense redwood and oak woodlands. Expect a good workout on the hilly terrain, with some sections offering moderately steep inclines and others providing a more challenging climb.

If you only do one ride, we'd point you towards the challenging Old Mine Trail (lower) ๐ŸŒฒ loop from Mill Valley. At 29.5 miles (47.4 km) with significant elevation gain, it's a fantastic way to experience the preserve's varied ecosystems and panoramic Bay Area views. For a slightly shorter, but still difficult, adventure, the Marincello Trail โ€“ Sausalito โ€” Mill Valley Path loop from Alta covers 20.4 miles (32.9 km) and offers a great mix of terrain. More than 600 gravel bikers have already explored Camino Alto Open Space Preserve with komoot, and we're confident you'll find your next favorite ride here too.

If you only do 3 of these routes

  1. 1

    Old Mine Trail (lower) ๐ŸŒฒ loop from Mill Valley
  2. 2

    Marincello Trail โ€“ Sausalito โ€” Mill Valley Path loop from Alta
  3. 3

    Fern Creek and spring loop from Mill Valley

Compare these routes at a glance

Trail

Distance

Elevation

Difficulty

Old Mine Trail (lower) ๐ŸŒฒ loop from Mill Valley

47.4ย km

1,270ย m

Hard

Marincello Trail โ€“ Sausalito โ€” Mill Valley Path loop from Alta

32.6ย km

570ย m

Hard

Fern Creek and spring loop from Mill Valley

35.0ย km

930ย m

Hard

Phoenix Lake โ€“ Fish Gulch trail junction loop from Mill Valley

45.7ย km

1,180ย m

Hard

Bothin Marsh Preserve โ€“ Tennessee Valley Trailhead loop from Mill Valley

19.6ย km

430ย m

Moderate

Fish Gulch trail junction โ€“ Phoenix Lake loop from Mill Valley

51.6ย km

1,200ย m

Hard

Camino Alto Road โ€“ Pickleweed Inlet crossing loop from Larkspur

27.1ย km

580ย m

Hard

Marincello Trail โ€“ Bothin Marsh Preserve loop from Mill Valley

18.8ย km

300ย m

Moderate

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1.

Old Mine Trail (lower) ๐ŸŒฒ loop from Mill Valley

47.4km

04:21

1,270m

1,270m

Hard gravel ride. Very good fitness required. Mostly paved surfaces. Suitable for all skill levels.

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4.

Phoenix Lake โ€“ Fish Gulch trail junction loop from Mill Valley

45.7km

03:59

1,180m

1,180m

The Phoenix Lake โ€“ Fish Gulch trail junction loop from Mill Valley offers a demanding yet incredibly scenic gravel biking adventure. You'll wind through diverse landscapes, from the cool shade of redwood forests to sun-drenched oak woodlands and open grasslands, with the promise of sweeping views of the Pacific Ocean and Golden Gate Bridge from higher points near Mount Tamalpais. This route is a true test of endurance, featuring steep and loose sections that demand very good fitness and bike handling skills.

Planning your ride requires a bit of foresight; while much of the loop is prime for gravel biking, be aware that the immediate trails around Phoenix Lake itself may not allow bikes. Parking is generally available in Mill Valley, but it's always wise to arrive early, especially on weekends, to secure a spot. Given the route's length and elevation, pack ample water and snacks, and consider starting early to make the most of the daylight.

This loop is a standout in the Mill Valley area, celebrated by local gravel bikers for its challenging terrain and the opportunity to combine dirt climbs with rewarding road descents. It showcases the region's extensive trail network and significant elevation gains, making it a prime destination for those looking to push their limits and experience the natural beauty of Marin County.

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7.

Camino Alto Road โ€“ Pickleweed Inlet crossing loop from Larkspur

27.1km

01:59

580m

580m

The Camino Alto Road โ€“ Pickleweed Inlet crossing loop from Larkspur is a challenging gravel biking route that stitches together the best of Marin County's varied terrain. You'll navigate the dirt and gravel of Camino Alto Fire Road, enjoying views of Mount Tamalpais and the San Francisco Bay, before transitioning to the paved paths around Pickleweed Inlet, known for its scenic wetlands and diverse birdlife. This difficult 16.9 miles (27.1 km) loop offers a dynamic ride for those who love a mix of surfaces and scenery.

Planning this adventure requires a bit of foresight, as you'll be combining different trail systems. With 1918 feet (584 metres) of elevation gain and an estimated duration of 1 hour and 59 minutes, ensure your bike is equipped for both rugged fire roads and smooth paved sections. Starting early is advisable to make the most of the day and avoid potential crowds, especially on the more popular sections.

Marin County is renowned for its gravel biking opportunities, and this route exemplifies the region's ability to blend natural beauty with active recreation. Pickleweed Inlet itself is a significant wetland, home to endangered species and a crucial resting ground for shorebirds, adding an ecological dimension to your ride. This loop offers a unique way to experience the area's diverse landscapes, from forested hillsides to bayfront wetlands.

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Tips from the Community

Eric Cross
August 10, 2025, Phoenix Lake

log cabin at phoenix lake

1

0

Arrival of the magnificent Golden Gate crossing

Translated by Googleโ€ข

0

0

Good vantage point.

Translated by Googleโ€ข

0

0

Jude
April 6, 2025, Coastal Trail

Super fun

0

0

roukir
November 23, 2023, Sausalito Waterfront

A nice place, but the bike parking fee and the price of an ice cream are a complete rip off!

Translated by Googleโ€ข

0

0

Sue
October 26, 2023, Bothin Marsh Preserve

This tidal sanctuary runs along the Mill Valley-Sausalito Pathway and the Charles F. McGlashan Pathway. More than 400 species of migratory birds rest here after their long flights, and if you pass through in the early morning or late evening, the sunrises and sunsets reflect beautifully on the surface of this 106-acre marsh.

0

0

From easiest to hardest climbs out of phoenix lake from this junction: -Shaver Grade, easy grade, longer, shaded and pretty -Eldridge Grade, medium, good length and can connect you to mt tam east peak -Fish Grade fire road, very steep, we hiked the bikes

1

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Frequently Asked Questions

How many gravel bike trails are available in Camino Alto Open Space Preserve?

There are over 40 gravel bike trails in Camino Alto Open Space Preserve. These routes offer a diverse range of experiences, from moderately challenging climbs to more relaxed excursions on wide fire roads.

What kind of difficulty can I expect on the gravel bike trails in Camino Alto Open Space Preserve?

The trails in Camino Alto Open Space Preserve offer a mix of challenges. You'll find routes with moderately steep inclines, as well as more demanding options with significant elevation changes. While there are 11 moderate routes, the majority, 31 routes, are considered difficult, providing rewarding climbs for experienced riders. For example, the Lagunitas Trail loop from Corte Madera is a difficult route featuring substantial elevation changes.

What kind of views can I expect while gravel biking in Camino Alto Open Space Preserve?

Gravel biking in Camino Alto Open Space Preserve offers breathtaking panoramic views. From various points along the trails, you can see the San Francisco skyline, the Bay Bridge, and even the distant peaks of Mount Diablo. Stellar views of Mount Tamalpais are also a consistent highlight on many routes.

What natural features and ecosystems will I encounter on the trails?

The preserve boasts a rich variety of habitats. You'll ride through grasslands, oak and bay woodlands, and stands of redwood and Douglas fir. Coast live oaks, madrone, California bay, toyon, and coyote brush are prevalent, contributing to the preserve's lush feel. Sheltered areas also feature redwoods and California bay trees.

Are there any specific trails or fire roads known for gravel biking?

Yes, the preserve's network largely consists of wide fire roads ideal for gravel biking. Notable examples include Escalon Fire Road, Middle Summit Fire Road, and Camino Alto Fire Road. These multi-use trails provide varying levels of challenge, from nearly flat stretches to moderately steep inclines.

Are there any interesting landmarks or points of interest along the gravel bike routes?

Yes, several points of interest enhance the riding experience. You can explore sections like Camino Alto Road, the Middle Summit / Escalon Fire Road, and the Camino Alto OSP - Fire Road Trailhead. The Bob Middagh Trail also offers a unique experience.

Can I connect to other preserves or longer routes from Camino Alto Open Space Preserve?

Absolutely. Camino Alto serves as an excellent staging area for longer rides. It connects to adjacent preserves like Blithedale Summit and Horse Hill Open Space Preserve, allowing you to incorporate it into extensive gravel routes that explore the broader Marin County area, including connections to Mount Tamalpais.

What do other gravel bikers enjoy the most about gravel biking in Camino Alto Open Space Preserve?

The area is highly rated by the komoot community, with an average score of 4.6 stars from over 15 reviews. Reviewers often praise the diverse terrain, stunning panoramic views of the San Francisco Bay Area, and the well-maintained network of fire roads that make for an engaging gravel biking experience.

Are there any loop trails suitable for gravel biking?

Yes, many of the gravel bike routes in Camino Alto Open Space Preserve are designed as loops. For example, the Pantoll Road loop from Mill Valley and the Marincello Trail โ€“ Sausalito โ€” Mill Valley Path loop from Alta are popular options that allow you to start and finish in the same location.

Is Camino Alto Open Space Preserve dog-friendly for those who want to bring their pets?

Yes, Camino Alto Open Space Preserve is known for being dog-friendly, making it a popular spot for local residents and their canine companions. Many of the multi-use trails are suitable for dogs, but always ensure they are on a leash and follow preserve regulations.

Is there ample parking available at the trailheads?

Yes, Camino Alto is considered an ideal neighborhood preserve with ample parking available, particularly at the Escalon trailhead, providing easy access to the trail network.

Are there any trails with waterfalls in or near the preserve?

While not directly within the main gravel biking fire roads, the Dawn Falls Trail, which can be accessed from the preserve, offers a pleasant redwood forest experience along Larkspur Creek, leading to seasonal waterfalls. This could be a nice addition to a gravel ride if you're looking for a short hike.

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