The reserve is more than 2,000 acres, and is surrounded by thousands more acres of dense forest full of steep ravines, lava rocks, giant ferns and thick vegetation that often must be hacked with machetes.

Ms. Eller had intended to go on a short trail walk, one she had done before. She went off the path at one point to rest, and when she resumed hiking, she got turned around.

“I wanted to go back the way I’d come, but my gut was leading me another way — and I have a very strong gut instinct,” she said. “So, I said, my car is this way and I’m just going to keep going until I reach it.”

Ms. Eller estimated that she had hiked continuously from 10:30 a.m. until around midnight that first day, looking for her car.

The same determination that led her astray would push her to stay alive.

“I heard this voice that said, ‘If you want to live, keep going,’” she said. “And as soon as I would doubt my intuition and try to go another way than where it was telling me, something would stop me, a branch would fall on me, I’d stub my toe, or I’d trip. So I was like, ‘O.K., there is only one way to go.’”