Last updated: December 3, 2025
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Visit Astonishing National Natural Landmarks
National Natural Landmarks (NNLs) are natural areas that contain significant examples of the nation's biological and geological features. The 600+ NNLs are designated by the Secretary of the Interior as the best examples of a type of biological community or geological feature. The National Park Service works cooperatively with landowners, managers, and partners to conserve these sites.
Since NNLs are relatively unknown compared to more popular park sites, they can sometimes serve as less busy alternatives. However, NNL status does not indicate public ownership and each NNL is managed differently. Some may not be open to the public. So, it's important to know before you go and research the site before your visit.
If you need a starting point, the following are some of our favorite NNLs that are open to the public and have some amazing natural features!
If you need a starting point, the following are some of our favorite NNLs that are open to the public and have some amazing natural features!
Hidden Gems
Oregon
Fort Rock State Natural Area
Fort Rock, formed 10–12K years ago, is a tuff ring created by volcanic explosions beneath a lake, later eroded into its crescent shape.
Washington
Ginkgo Petrified Forest State Park
Home to North America's most diverse Miocene petrified wood site with 40+ wood types, plus Ice Age Flood features that shaped the land!
Florida
Corkscrew Swamp Sanctuary
Walk the boardwalk to discover a living treasure trove of biodiversity & the largest remaining old-growth bald cypress forest in the South.
North Carolina
Stone Mountain State Park
Discover a massive granite monadnock with rare, endemic plants—perfect for exploring geology, unique habitats, and scenic views.
Texas
Caverns of Sonora
Coralloid growths (cave popcorn) & bladed helictites are just some of the rockin’ formations that await visitors to this underground wonder.
Arizona
Barringer Meteor Crater
What does it look like when a 150-foot-wide iron-nickel space rock (aka meteor) hits Earth? Check out this northern Arizona crater to see!
Pennsylvania
Cook Forest State Park
Experience the towering pines and hemlock of the Forest Cathedral in this relict, old growth forest in northwestern Pennsylvania.
Connecticut
Dinosaur State Park
Journey to the early Jurassic and view 200-million-year-old fossil dinosaur footprints right in central Connecticut.
Minnesota
Cedar Creek Natural History Area
Helen Allison Savanna Preserve - Discover an internationally famous landscape where forests, prairies & wildlife meet.