Natalie Griffin and Jenna Santos had just spent two days in Humboldt County in northern California visiting friends when the high school pals were making the three-hour drive back home to Castro Valley Wednesday evening.
It was raining as they drove south on Highway 101 through Mendocino county, with Santos at the wheel and Griffin texting her boyfriend. “The next thing I knew we were hydroplaning, then we were upside down and I felt this really big impact on my head,” Griffin, 19, tells PEOPLE, of the terrifying seconds as the car flipped over and landed right-side up in a raging creek swollen by rain.
“At first, I didn’t know I was in the water,” says Griffin. “I thought she was driving, the river was moving the car so fast.”
After that, the car began filling up with water. “We started to panic and we were saying, ‘Oh my God, oh my God,” she says. “We were freaking out.”
The pair kicked the already-cracked windshield to escape, but the holes they made only helped the vehicle fill with water even faster.
“I said I have to calm down, if I kept panicking I wasn’t going to get out of it,” she says. “When the water was at our necks, Jenna was crying and I realized the back window was open, that the water was filling in the front and the back was sticking out of the water.”
The plan was for both to escape through the back. “I climbed out of it and jumped into the river, it was really cold and really high and fast because it was raining.”
The water slammed her into a tree. “I remember reaching from the water and grabbing onto a branch and I pulled myself up,” she says. “I was in shock, completely scared out of my mind.”
Griffin looked beneath her and saw the car; she knew Santos was still inside, but the strong current prevented her from reaching her.
“That was one of the scariest parts, I thought it was a nightmare, I was so in shock that my friend was in the car, dead,” says Griffin. “I really thought this was a bad dream.”
The events of the next 12 hours continued to be a nightmare.
A cold, hard rain fell most of the night as Griffin positioned herself on top of a branch. She wrapped a light jacket around her body — clad in Lululemon workout pants and an Under Armour shirt — in an attempt to create warmth.
“I was crazy shivering, uncontrollably, the whole night, it was absolutely freezing,” she says. “At some point, I thought I was going to die. At first, I was crying, but during the night I didn’t cry at all, I was just trying to stay positive.”
A devotee of yoga and mindfulness meditation, Griffin tried to calm down with deep breathing and stretches, and focusing on her good fortune that at least she was alive.
Griffin either hallucinated or dreamed — she isn’t sure — that Santos was with her through the night. “She was there talking to me,” says Griffin. “She said, ‘It’s OK, you can’t think you are going to die.'”
At the crack of dawn, Griffin decided to swim the short distance from the tree to the shore. As soon as she got back in the frigid water, the current whisked her into a patch of vines that caught onto her neck and stomach and pulled her beneath the water. “I thought I was going to die,” she says.
Griffin, who considers herself a bad swimmer, serendipitously thought she could escape the vines by diving beneath them. “It was crazy for the idea to come,” she says. “It seemed like something divine, like God.”
It worked. Now freed, the current swept her to an embankment in the stream; from there she made it to the nearby shore.
“I couldn’t walk, I couldn’t move,” Griffin says. “I could barely stand and at one point I fell and said, ‘I can’t do it.'”
But she did, crawling up a small hill covered in berry bushes to the roadside.
“I was so relieved, so happy, it was the happiest day of my life, I was waving my arms and the first truck I saw stopped,” she says. The driver put her in the truck and turned on the heater. “I told him I am so cold,” she says, “the coldest I’ve ever been.”
The trucker called 911, and let Griffin use his phone to call her family. An ambulance transported her to a nearby hospital, and Griffin was told her body temperature was 90 degrees. She also had a sprained ankle from the crash.
By that night, Griffin was home with her family, elated about her survival. The next day, however, and all the days since, the pain of Santos’ loss has been devastating. “I couldn’t stop crying for the last couple of days,” Griffin says. “This girl, who is like a sister to me, is just gone. It’s overwhelming and very sad.”
Santos was an only child, raised by a single mom without much financial means, says Griffin, a sophomore at a junior college. Santos attended Humboldt State and was working on transferring to UC-Berkeley to pursue a career in psychology.
“She was always positive, she always found the good in people, she always wanted to make someone feel better, one of those people always bubbly,” says Griffin, whose family has set up a GoFundMe page to help pay for Santos’s funeral costs. Says Griffin: “We want to do all we can to help them.”
The crash is under investigation, a dispatcher with the California Highway Patrol tells PEOPLE.