Melissa Aurand of Eagan told the Cloquet Pine Journal she was aboard Stormy, following behind her husband Zach as they followed the Willard Munger State Trail the evening of May 7.
"All of a sudden, Stormy started to sort of topple sideways," Melissa
Aurand said. "I thought maybe she had passed out or something. I was tossed off just as her back legs began to slip into the ground.
"The horse was slowly sinking into the ground, like she was in quicksand."
Zach tried unsuccessfully to pull Stormy to safety, so Melissa used her cellphone to place an emergency call for help, the newspaper said.
When members of the Wrenshall Fire and Rescue Squad showed up, they found Zach down in the deep hole with the horse.
"The man was about 6 feet tall, and when we got there all we could see was the top of his cowboy hat," said Peter Laveau, first assistant chief. "The hole must have been 9 or 10 feet deep."
The rescuers used shovels to dig out a path for Stormy to climb out of the hole.
Stormy remained pretty calm throughout the ordeal and emerged with only a small cut on a shoulder.
"She's the most amazing horse ever," Melissa said.
Laveau said the sinkhole may have been created by a combination of flooding last June and the winter cycle of freezing and thawing that damaged a culvert.