RCMP Cpl. Scott MacRae said ground crews spent the night combing the trails near the Baddeck Cabot Trail Campground, but haven't found any trace of Mariette Forest of Sherbrooke.
"Workers do need to get rest time, but they're such dedicated people, people will come in to replace them," he said.
Police said Forest left the campground to go for a hike on the nature trail around 8:30 a.m., but was reported missing two hours later.
They said it's not unusual for her to go on a hike, but searchers are worried about her health.
She was last seen wearing a checkered orange and black jacket, jeans and running shoes. She was also carrying a walking stick.
Forest is described as slightly built, about five feet tall and white.