(CNN) -- Mark and Kristine Wathke knew they were going to die.
Stuck in a foot of snow on a road somewhere outside Yellowstone National Park in Wyoming, the couple from Wisconsin pulled all the clothes out of their suitcases and wore them, trying to keep warm in their car with temperatures dipping below zero.
They rationed the bread and water they had with them, and ran the car's engine periodically to get some heat. There was no service for their cell phone.
This wasn't the end they'd envisioned for their national parks tour.
The Wathkes left Yellowstone's northeast entrance on October 29 at 4 p.m., planning to head to Montana. They plugged the address for their hotel into Google Maps and hit the road. Their route took them on Beartooth Highway, but they said they didn't see any signs warning that the road was closed.
In fact, the highway was shut down in mid-September due to heavy snow, with signs posted saying so, the Park County Sheriff's Department said.
The Wathkes' Kia got stuck several miles in. They thought for sure they'd be found, probably the next day. But it didn't happen, and with each passing day, their hopes dimmed, they told the Billings Gazette.
They decided to write letters to loved ones, and recorded a message saying goodbye.
Meanwhile, Troy Barnett, who owns the K Bar Z Guest Ranch near Cody, Wyoming, heard about the missing couple when his wife spotted it on Facebook Sunday night.
"I decided about 9 o'clock that it was too late to go out," Barnett told CNN.
Monday morning, Barnett got out the snowmobile he hadn't used since last fall, made sure it was in running order, loaded it into his pickup truck and set out to look for the Wathkes.
"There are only two roads in this area, so I kinda knew what road they needed to be on," he said.
He drove for more than 20 miles, until he couldn't anymore because of the snow. Then he got on the snowmobile and minutes later, found the couple just about where he thought they'd be.
"The car was stuck in the middle of the road. It wasn't buried but it had some snow on top of it. It kind of worried me a bit, and there was no movement," Barnett remembered.
Inside the car, the couple heard something.
"Mark heard it first and he was like, 'Kris! Kris! Kris!,'" Kristine Wathke told the Billings newspaper. "We saw him coming up the road and I was just crying."
Barnett parked right next to the vehicle, and the door opened.
"They were really grateful and there were some tears," he said. "I asked if everyone was okay and if they need medical attention and if they were warm enough."
Barnett loaded Mark and Kristine on his snowmobile and drove back to his truck. He called a friend with a radio and had him get in touch with the sheriff, and then took the couple to his house, where they called their family.
The sheriff says Barnett's actions saved the Wathkes' from serious harm.
"I commend him for his unselfishness," Sheriff Scott Steward said.
Barnett said it's not the first time he's helped someone in that area.
"We help people off there quite a bit," he said. "It's really rural up here, we're just up in the mountains."