Trapped inside a dark mine shaft, the dog was 100 feet below the surface.

When Michael Schoepf rappelled down that Corona-area mine with nothing but a thin rope, the dog’s eyes lit up.

“She knew this was a second chance,” he said.

Now, the focus is on finding the owner of the pit bull, likely one year old, or helping her get a new home.

Schoepf, who lives in Long Beach and works in Cypress for his dad’s sign company, was lowered by his buddy, Nick Gladden of Garden Grove. Dr. Keri Berka of Happy Tails Animal Hospital in Garden Grove treated the slightly injured dog for free.

“It’s an act of goodwill that has turned out great,” Berka said.

Schoepf, Gladden and other friends were off-roading late Friday night near Lake Mathews when they turned onto a road and discovered a mine shaft. Curious, flashlights were shone inside – a pair of eyes looked up.

“Let’s get some rope,” Schoepf told Gladden, 25.

“There was no way we were going to turn our backs and let her die,” Schoepf said later.

All they could muster was nylon rope, the kind you get at The Home Depot, in pieces that were tied together. The rope was wrapped around the 140-pound Schoepf, 23, who had worked in the telecom industry climbing up cellphone towers.

It took 20 to 30 minutes for Gladden to lower Schoepf. If a rock rubbed the thin rope the wrong way, it would have been “a rescue mission for me and the dog,” said Schoepf, chuckling.

Once he landed, “It was like an ‘Indiana Jones’ movie,” Schoepf recalled. “There were tarantulas all over the floor and walls. There was even a charred minivan.”

The dog, down in the mine for some reason for perhaps two days, knew.

“She climbed up right on me,” he said.

The men named the dog Corona.

Saturday, Schoepf took the dog into Happy Tails Animal Hospital where veterinarian Birka and her staff inspected Corona, waiving the $45 consulting fee and providing her with $50 in medication for free.

Generally in good health, Corona had a few scratches and suffered traumatic glaucoma in her left eye, something that could have happened if she fell down the shaft, Birka said, adding it can easily be treated.

Schoepf has posted a snippet of his adventure on Facebook, hoping to find the owner; the dog had a microchip but it wasn’t registered.

The media flocked. Schoepf and Birka have been fielding calls from around the country from those wanting to adopt Corona.

Schoepf and Gladden would prefer to find the owner. If not, they hope to find someone local who can take care of Corona. They can’t keep her themselves because they already have dogs. But they hope to visit from time to time.

“Every life is precious,” Gladden said.

Contact the writer: 714-704-3764 or jpimentel@ocregister.com