One of the best places to see just how popular some Minnesota state parks have become is Gooseberry Falls State Park, along the North Shore of Lake Superior, where the Gooseberry River cascades over a series of dramatic drops just a short walk from the highway.
More than 750,000 people visited the park last year alone. On a hot summer day last week, tourists took off their shoes and splashed in the pool below the falls, scrambled along rock ledges and snapped selfies.
Marcus Ervin drove up from Duluth for the day with his family.
"Oh, it's beautiful, it's peaceful, the family loved it," said Ervin, who was taking advantage of one of the first warm days of the year along the shore of Lake Superior.
"This gave us something different than just being in the city," he said. "Mother Nature, you know? That's what we came for."
All those people seeking out Mother Nature create some challenges at Gooseberry, said park manager Audrey Butts. The parking lot fills up quickly on busy days.
And solitude can be hard to come by.
"A lot of people want to get out and be the only one in the park, but unfortunately since there's so many people, it does get kind of crowded," said Grace Hill, park operations supervisor.
Not that Hill and others at the Minnesota DNR are complaining. State park visitation has increased 22 percent since 2003. That's twice as fast as the state's population has grown. Revenue from state park permit sales, helped in part by a fee increase, has jumped more than 80 percent in the past six years.
DNR officials attribute some of the growth in state park visitation to investments from the Legacy fund. That's the sales tax increase voters approved in 2008, which has paid for millions of dollars in park improvements.
The surge in park popularity has also coincided with a broader interest in getting outside. A recent survey the DNR conducted found that 70 percent of Minnesotans consider outdoor activities very important.
"People are starting to view the outdoors as a means to get away from all the demands of everyday life," said DNR visitor services and outreach manager Rachel Hopper. "It's also a good way to spend time with loved ones."
But the state's population is changing. It's getting older and much more diverse. And DNR officials say park visitation isn't keeping pace with those changes.
"Our most recent state park visitor survey showed that we only have about 5 percent of our visitors as identifying as people of color. So there's definitely a gap there," said Hopper.
To reach new audiences, 10 years ago the DNR launched an "I Can!" series of programs, where people nervous about getting outside learn outdoor skills like camping, fishing and canoeing.
More than 80,000 people have taken part so far, 60 percent of them people of color.
But it's not just about filling up state park campgrounds, officials say. The focus is also motivated by a growing body of research that shows getting outside is really good for you. Especially for kids.
"We often summarize the research by saying nature can help children be healthier, happier, smarter and better stewards of the environment," said Cathy Jordan, research director for the Minneapolis-based nonprofit Children and Nature Network.
The organization was founded more than a decade ago by Richard Louv, author of "Last Child in the Woods," who coined the term "nature deficit disorder" for the problems he saw from kids not playing outdoors.
Studies show that getting outside provides a host of benefits, from improving health and fitness and mental health to reducing stress, even improving performance at school.
"As Rich Louv once said, there's never been a study that has shown that nature is bad for you," said Jordan. "And while we don't know everything, we know enough to act."
Which is exactly why Moriah Loos of Rochester dragged her two daughters out for a hike at Gooseberry Falls State Park last week.
Loos, an elementary school teacher, said getting outside is a huge stress reliever for her. Especially when there isn't any cellphone service.
"We have some of our best conversations as a family when we're out hiking, and I enjoy that," she said. As for her kids, "I know eventually they'll enjoy it more. Right now we force them to go, but I think that as they get older it will be kind of ingrained in them — I hope."