There are more than 400 sites in the US National Park System. Here's why it's time to skip the most-visited top 10 and seek out quieter, equally spectacular ground.

Winding through one of the wildest corners of Colorado, 210,000-acres deep in Dinosaur National Monument, I found myself balancing sideways on the crest of the biggest wave in the river – somehow staying upright through the whirling Class IV rapids. That week, I paddled 71 miles down the Yampa River, Colorado's last free-flowing river, camping beneath towering red-and-orange striped canyons etched by ancient peoples. The experience left me with something rare: space to breathe and trust in the river to take its course.

Unlike marquee parks that strain under the pressure of mass tourism, Dinosaur has quietly struck a balance between visitation and protection. The original head of the Sierra Club, David Brower, saw its value back in the 1950s when he fought to stop a proposed dam on the Yampa. Without him, many of these canyons would now be underwater.

"The riparian zone on the Yampa River is the most natural stretch of river in Colorado," says Tom Kleinschnitz, director of Visit Moffat County. "Preservation of this resource is crucial for the natural habitat, and it is one of the last natural river sections that visitors can observe, enjoy and play in."

From Acadia's rocky coast to Yosemite's soaring peaks, the US has no shortage of iconic national parks. But visitation numbers continue to climb, often outpacing infrastructure and threatening the very environments they showcase.

To protect these wild places – especially as US national parks, forests and wildlife habitats are under threat of cuts and understaffing – long-time nonprofit partner of the National Park Service, Western National Parks has launched new itineraries spotlighting 72 lesser-known US parks and monuments.

"Our lesser-known parks are truly hidden gems," says Marie Buck, the association's president and CEO.

"They often offer a more intimate experience and an opportunity to understand the under-told stories that have shaped the nation. And they do all this often with fewer crowds." Since its founding, the nonprofit has contributed $162m to responsible visitation of US public lands.

Others are also encouraging off-the-beaten-path exploration. Former park ranger Ashli Nudd curates personalised national park itineraries; while Outdoorable, a company formed in the wake of potential NPS layoffs, is hiring former rangers to create custom trip itineraries and offer traveller tips. Even adventure travel company Intrepid Travel recently launched Active-ism tours through Zion and the Grand Canyon – with routes designed to avoid high-traffic areas and proceeds going to the National Parks Conservation Association and the Grand Canyon Conservancy.

Here are four underrated spots that prove you don't need to sacrifice beauty, biodiversity or a sense of wonder to travel responsibly this summer.

This rugged desert landscape spans 210,000 acres across Colorado and Utah, blanketed with of purple

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