Save the Redwoods League, in partnership with more than 25 California park agencies, is sponsoring free day-use admission to 100 different redwood parks Oct. 13 as part of its ongoing Free Second Saturdays program.

The free admission is part of the nonprofit agency’s yearlong celebration marking 100 years of saving the state’s redwood forests.

October’s special edition of the Free Second Saturday program offers more than twice the usual 40 destinations included in the program begun in January.

It’s a testament to the scenic riches of the North Coast that so many on the list are within reach of Sonoma County, including 13 that are inside the county proper.

They include: Armstrong Redwoods State Natural Reserve; Austin Creek State Recreation Area; Fort Ross State Historic Park; Gualala Point Regional Park; Grove of the Old Trees in Occidental; Jack London State Historic Park; Jenner Headlands Preserve; Kruse Rhododendron State Natural Reserve; North Sonoma Mountain Regional Park and Open Space Preserve; Riverfront Regional Park; Salt Point State Park; Sonoma Coast State Park; and Stillwater Cove Regional Park.

There also are 14 Second Saturday parks in neighboring Mendocino County and 10 in Marin County.

A complete list is available at www.savetheredwoods.org/get-involved/free-redwoods-days.

Some locations have a limited number of free passes, which are available online beginning Wednesday at 8 a.m. Free Second Saturdays continue Nov. 10 and Dec. 8.

You can reach Staff Writer Mary Callahan at 707-521-5249 or mary.callahan@pressdemocrat.com. On Twitter @MaryCallahanB.