A massive search is underway for a 20-year-old Oregon woman who is missing after going on a hike Sunday.

The family of Allyson Joy Watterson told Washington County authorities that they have not heard from her since Friday morning.

Authorities said the 20-year-old was last seen on Sunday in a wooded area near North Plains where she was hiking with her boyfriend.

Allyson Joy Watterson, 20, was last seen on a hike in Oregon with her boyfriend on Dec. 23. Her family had not heard from her since Dec. 21. (Washington County Sheriff's Office Handout)

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The sheriff’s office said Watterson and her boyfriend, Benjamin Hunter Garland, became separated during the hike and he was able to find his way out of the area. She was reported missing on Monday.

“Allyson is a free spirit, kind of your true definition of like, hippie,” her aunt, Billy Macy, told FOX 12. “She’s our girl.”

More than 30 search-and-rescue personnel and 70 volunteers are scouring the area where Watterson was last seen.

Tony Morris, the search coordinator, told reporters late Wednesday that the search area is difficult, with no designated trails. Instead, he said, it is mostly rural private properties with heavily wooded terrain, large bushes and some steep areas.

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Watterson is described as being a white woman, about 120 pounds and 5 feet 7 inches. She has a tattoo of an eye on the front of her left shoulder and another tattoo of a fairy sitting on a spider web on her left forearm.

Benjamin Hunter Garland was arrested the day after the disappearance of his girlfriend Allyson Joy Watterson. Authorities said the charges are unrelated to her missing. (Washington County Sheriff's Office)

Garland was arrested and remains in police custody at the Washington County Jail on charges unrelated to Watterson’s disappearance. FOX 12 reported Garland was arrested Monday night after he was found inside another man’s truck across from the search area.

“He was soaking wet from head to toe and he was kind of in a bad way, so I gave him a ride home to his parents’ house in Hillsboro and didn’t really think anything of it until today when I saw the people out here searching for the young girl that’s missing,” neighbor Ralph Medica told the news outlet.

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Anyone with information is asked to call the Washington County Sheriff’s Office's non-emergency number, 503-629-0111.