Ray and Maranda Ankofski were visiting the area for the third time in as many years, and were supposed to be back on Monday.
Ray's sister, Judy Lamb, said the family hasn't spoken to them since Friday.
"We're all devastated," Lamb said. "There's no way to describe it."
She said her brother and sister-in-law are big outdoors people who have ample experience hiking, camping, and riding utility terrain vehicles.
A UTV that they were riding has been located in the Steel Bender Off-Road Trail area, but Ray and Maranda have not.
"It's flipped over, heavily damaged," Lamb said of the UTV.
Authorities have also found things like the couple's cooler and his rain jacket.
One issue complicating matters is that the region experienced heavy rains Friday that had the Grand County Sheriff's Office having to rescue 20 people in a single mission.
It's unknown if the rain directly caused the Ankofskis to go missing.
"We can only really only assume," Lamb said.
One thing she isn't doing? Losing faith.
"We're not giving up hope," she said. "We're all praying."
The Grand County Sheriff's Office said they're currently employing ground teams, helicopters, dogs, and other equipment in their search.
Lamb added that volunteers in the community are also participating.
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