Deer Island Open Space Preserve,
Marin County Open Space District,

Marin County
In brief:
1.8 mile loop round the base of a little hill. Good hawk watching.

Distance, category, and difficulty
This 1.8 mile loop hike is easy, with about 140 feet in elevation change.

Shaded at first, than mostly exposed.

Trail traffic

Trail surfaces
Dirt trails.

Hiking time
Less than 1 hour.

Nice year round.

Getting there
From US 101 in Marin County, exit San Marin Drive/Atherton Avenue. Drive east on Atherton Avenue for about 1.7 miles, then turn right on Olive. After about 0.6 mile, turn left on Deer Island Lane. After about 0.2 mile bear right and look for the small parking area by the Open Space sign.

Get driving or public transit directions from Transit and Trails:

GPS coordinates* for trailhead
Latitude 38 6'8.00"N
Longitude 12232'20.63"W

(* based on Google Earth data, shown as degrees, minutes, seconds)

Gas, food, and lodging
Gas, pay phone, stores, and restaurants available back to the west in Novato. No camping.

Trailhead details:
Parking for about 4 cars. No entrance or parking fees. No toilet facilities, drinking water, or maps are available. No designated handicapped parking, and trails are too narrow for wheelchairs. There is no direct public transportation to this trailhead.

No bikes. Trails are open to hikers and equestrians. Dogs are permitted on leash only.

The Official Story:
MCOSD's Deer Island page
MCOSD field office 415-499-6405

Map Choices:
• Download the pdf map from the MCOSD website.
Trails of Northeast Marin County is my favorite map (available from Pease Press).
• Open Spaces, by Barry Spitz, has a decent map, with trail and preserve descriptions (order this book from
North Bay Trails, by David Weintraub, has a detailed topographic map and preserve description (order this book from
Hiking Marin, by Don and Kay Martin, has a good map and short preserve description (order this book from

View photos from the featured hike.

Go to Bay Area Hiker Home page

One of the first things you may notice at Deer Island is that it is a popular place for dog walking. TrailheadAlmost any time of day you'll likely cross paths with locals and their canine friends. Deer Island's easy 2-mile loop trail provides terrific daily exercise for man and beast (as well as grandma, mom, and child). The loop trail skirts this 134-acre preserve oddly situated on the edge of a mixed industrial and residential neighborhood, where you'll find oak grassland, California bay woods, and substantial wildlife. I think of Deer Island as a real island; a sea-level enclave where a little ecosystem thrives.
        Start at the junction immediately past the entrance stile. Bear left on signed Deer Island Loop Trail. The narrow flat trail, open to hikers and equestrians only, runs through grassland, parallel to a road servicing a junkyard and storage units. Be grateful to be on this side of the fence.Deer Island Loop Trail In August and September you may notice the "local color," as the preserve's ample supplies of poison oak turn brilliant red. Deer Island Loop Trail climbs gently through a dense patch of California bays. As the woods thin to mixed oak grassland, traffic sounds from Atherton Avenue and CA 37 are audible. But on Deer Island, it's amazing to witness the dramas of the natural world. You may see geese flying in formation and a woodpecker settling on an overhead branch. On one hike, copious amounts of skunk fur were scattered under a California bay. Vultures and hawks commonly keep a look out for squirrels preoccupied with acorn hunting. Many of Deer Island's small mammals dine happily on curly dock; the reddish seeds of that plant are evident in their scat in autumn. In spring, you might see purple Ithuriel's spear and bluedicks. Deer Island Loop Trail winds under mostly California bays, with a few white oak, coast live oak, and buckeye for company. There's a huge fig tree on the left side of the trail, ignored and gnarled, but still producing fruit. At 0.44 mile, a spur trail heads out of the preserve to the left. Continue on Deer Island Loop Trail. Deer Island Loop TrailJust a bit further along, De Borba Trail heads uphill at a signed junction at 0.58 mile. (This trail is an option. For a hike that's a little shorter, but with more elevation change, turn right and ascend to the preserve's high point, then descend to the junction with Deer Island Loop Trail, a few feet from the trailhead.) Remain straight on Deer Island Loop Trail.
        The marshes of Novato Creek, and water treatment ponds are visible on the left. Look for two shallow caves off to the east (hill) side of the trail. I've always been too chicken to check them out. Coast live oaks dominate the landscape, but also look for blue and black oaks (most conspicuous in autumn when they shed their leaves). One August when I was here, thistles had shed their seeds and it appeared to have snowed along the trail. I think this stretch of trail is the loveliest, with a view to Big Rock Ridge across 101, and graceful coast live oaks and buckeyes in the grassland. A view back on Deer Island Loop TrailYou will probably see raptors overhead, and deer are common. In the winter the air is still and the hillsides brighten with green fresh grass. By May, the grass is waist high and choked with thistles. Deer Island Loop Trail passes a perfectly shaped buckeye tree. In mid spring the sweet smell of its blossoms waft through the air. At 1.76 miles, a dead-end path, Russell Antonio Trail, begins on the left. Stay to the right on Deer Island Loop Trail.
      You'll pass an old fallen-down house to the left. On a May hike here, I came upon a dead squirrel in the middle of the trail. The squirrel had obviously not died a natural death. Bobcat or coyote? I couldn't tell. As you return to the parking lot, a few steps before the end of the loop, the other end of De Borba Trail meets Deer Island Loop Trail at a signed junction. Continue straight to the trailhead.

Total distance: 1.78 miles
Last hiked:  Wednesday, May 9, 2001