Esther Dingley, 37, was last seen on November 22, according to a Facebook post from her partner, Dan Colegate, published Saturday. The couple have been traveling around Europe since 2014, documenting their adventures on social media.
"I'm broken. Shattered to report that my beloved Esther, the person who taught me how to feel, is missing," Colegate wrote on the couple's shared page, "Esther & Dan."
"Search and rescue teams have so far found no trace of her."
Dingley was last seen November 22 on the Spanish side of the mountains, a spokesman for the local mountain rescue team, PGHM, told CNN.
Sixteen team members have been searching for Dingley with the aid of a helicopter but so far they have not found any sign of her, the spokesman said.
"Anyone who has seen or come into contact with this hiker is asked to contact PGHM Bagnères de Luchon," the mountain rescue team wrote in a Facebook post Friday. "We are facing an emergency situation."
Dingley set out on her hike on November 22 and was scheduled to return on November 25, according to the post. Her planned route took her between the Port de la Glère and Port de Vénasque mountain passes, PGHM said.
The couple started traveling around Europe in a camper van in 2014 after Colegate suffered a serious illness. Since then they have been documenting their journey on social media.
Colegate asked people to send "prayers, thoughts, candles and whatever you have," in his Facebook post.
"I've not been saying anything, but this wonderful person believes in the power of positive thought and right now I'll take anything if it means that she can be found," he wrote. "I need her back. I can't face the alternative."
Colegate has written a number of books about how their lives changed in the wake of a near-death experience, and various media outlets have published articles on the couple. On November 22, the BBC published an article about the pair and their life on the road.