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Serpentine Loop Trail



2.7 mile 4.4 kilometer loop
80% Runnable


Ascent: 625' 191 m
Descent: -622' -190 m
High: 1,030' 314 m
Low: 552' 168 m


Avg Grade: 9% (5°)
Max Grade: 23% (13°)


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Trail shared by Joan Pendleton

A hilly trail through the woods and grass hills of Calero County Park.

Joan Pendleton

Features Lake · Views · Wildlife

The park is open 8 a.m. to sunset. There is no fee when parking in the trailhead parking area.


Serpentine Loop Trail is amidst the wooded and grass hills of Calero County Park. From the trailhead parking area, it can be reached by running either Pena Trail or Figueroa Trail, to their end points, where Serpentine Loop Trail starts and ends. See the descriptions for Pena Trail and Figueroa Trail. One can also get to Serpentine Loop Trail from Cottle Trail, via the Serpentine Loop Trail Connector.

This description follows a counterclockwise route around Serpentine Loop Trail.

Serpentine Loop Trail is basically flat at first as it winds around through the grass and wooded hills, headed toward Calero Reservoir. Calero Reservoir soon comes into view and so do the deer. The trail descends with the reservoir off to the right. At mile 1.2, the Serpentine Loop Trail Connector, a short 0.2 mile connector to Cottle Trail and future new trails, is reached.

Passing Serpentine Loop Trail Connector, Serpentine Loop Trail starts to ascend, steeply in places, to its high point at the 1.8-mile mark. The views are great as the trail climbs. From its high point, in the distance the Santa Cruz Mountains with Mt. Umunhum to the west and the Diablo Range to the northeast can be seen. All around nearby are views of the beautiful grass and wooded hills and valleys of Calero County Park.

From its high point, Serpentine Loop Trail descends before rolling up and down through grass and woods to end where it started, at the Pena Trail and Figueroa Trail junction.

Flora & Fauna

Wooded, primarily oak, and grass hills. Deer.

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Land Manager: Santa Clara County Parks

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5 Views Last Month
204 Since Jan 19, 2018



The Calero Bat Inn is a daytime retreat for local pest-eating mammals. A fence keeps you from getting close and disturbing their sleep.
Apr 1, 2019 near Almaden…, CA
The Santa Cruz Mountains and Mt. Umunhum in the distance (left of center), from the high point of Serpentine Loop Trail, looking west
Jan 19, 2018 near Almaden…, CA
The Diablo Range can be seen in the distance looking east-northeast, just before Serpentine Loop Trail drops amid the grass and wooded hills of Calero County Park.
Jan 19, 2018 near Almaden…, CA
The wooded and grass hills of Serpentine Loop Trail.
Jan 19, 2018 near Almaden…, CA


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