National Park service rangers are searching for Seattle hiker and author Karen Sykes, who was reported missing on Wednesday, June 18 near Mount Rainier National Park while doing research.

According to Reuters, the 70-year-old hiking enthusiast was reported missing when she didn't return from Owyhigh Lakes Trail. She had been hiking alone over a snow-covered stretch, a spokeswoman for the park said.

Sykes is the author several of newspaper articles and books on hiking in Mount Rainier Natonal Park, and is widely known in the Pacific Northwest area as a local authority on outdoor recreation.

Sykes' friend Don Geyer, said Sykes and her partner Bob Morthorst planned to spend the entire day Wednesday hiking up Owyhigh Lakes Trail, reports The Seattle Times. However, Morthorst took a lunch break at around 5,000 feet in elevation, while Sykes continued on and said she would be back in an hour.

Geyer, who had hiked with Sykes about three times before, says that hiking is her passion. She's 70 years old but she is energetic and often goes on 13-mile runs. He also said that Sykes hikes at a quick pace without taking frequent breaks.

Sykes is the author of “Hidden Hikes” and co-wrote “Best Wildflower Hikes: Washington.”