The missing woman, Magdalena Glinkowski, is described as white woman with blonde hair and blue eyes, sheriff's Lt. Doug Pittman said.
Glinkowski is around 5 feet 7 inches tall and weighs about 120 pounds with a slim build, according to California State Park rangers.
Glinkowski's disappearance came to the attention of California State Park rangers on Friday when they noticed a car rented in her name was left abandoned in a parking lot near the Pantoll Campground on Mt. Tamalpais, Pittman said.
Park rangers attempted to contact Glinkowski at her Menlo Park residence where they learned she had not been seen at home since Sunday, March 30, the lieutenant said.
Before leaving home, she left a message that she was going on a day hike, but did not give a destination, according to Pittman.
Pittman said the rental car company told investigators Glinkowski continuously drives a rental car for months on end and that they were surprised when she failed to either return or renew her car at the beginning of this month.
Sheriff's deputies located footage from a security camera that captured a video of Glinkowski walking across the "Bootjack" parking lot last Sunday around noon near where her vehicle was later discovered, according to the lieutenant.
The video shows her wearing a pink-colored pullover top, light blue shorts, and white and black running shoes with green soles.
California State Park officials and the Marin County Sheriff's Search and Rescue Team are working together to search Mt. Tamalpais State Park for Glinkowski, Pittman said.
The Search and Rescue Team lead over 80 volunteer searchers and eight search dogs on a large-scale ground and air search for the missing woman on Saturday morning, Pittman said.
Volunteer search teams from sheriff's offices in Contra Costa and Alameda counties and the Bay Area Mountain Rescue Team from San Mateo County provided additional assistance.
The California Highway Patrol and the Marin County Sheriff's Air Patrol Unit spearheaded the search from the air, Pittman said.
Search and Rescue teams will continue to look for Glinkowski this morning, operating from a command post at the Pantoll Ranger Station on the crest of Panoramic Highway between Mill Valley and Stinson Beach, Pittman said.
According to Glinkowski's LinkedIn profile, she is employed as a software developer for the Massachusetts Institute of Technology as well as at Purple Encoding in the Bay Area. She previously worked for Microsoft and Intel.
Her LinkedIn page also states that she enjoys running and jogging, and that she is fluent in English, Russian, Polish and French.
Glinkowski's whereabouts remains under investigation and anyone with information is encouraged to contact the Marin County Sheriff's Investigations Unit at (415) 473-7265 or Bay Area Crime Stoppers at (800) 222-TIPS.