There are 18 National Natural Landmarks in the U.S. state of Washington, out of nearly 600 National Natural Landmarks in the United States.
| Name | Image | Date | Location | County | Ownership | Description | |
|---|---|---|---|---|---|---|---|
| 47.8786°N -119.8017°W | Federal, state | The most illustrative examples of glacial erratics in the United States. | |||||
| 48.2438°N -119.7518°W | State, private | One of the largest and least disturbed examples of antelope bitterbrush-Idaho fescue shrub steppe remaining in the Columbia Plateau. | |||||
| 46.975°N -119.1964°W | Federal, state, private | Illustrates the dramatic modification of the Columbia Plateau volcanic terrain by late Pleistocene catastrophic glacial outburst floods. Includes Columbia National Wildlife Refuge. | |||||
| 46.9489°N -120.0028°W | State | Thousands of logs petrified in lava flows. Part of Ginkgo/Wanapum State Park. | |||||
| 47.7667°N -119.2167°W | Federal, state, private | An illustration of a series of geological events. | |||||
| Private | The best example of basalt dikes, the congealed feeder sources of the Columbia River basalt plateau. | ||||||
| Federal | A 1500feet deep canyon that follows a tortuous path along meanders. | ||||||
| 47.4583°N -119.8°W | State, private | Largest and best example of a pendent river bar formed by catastrophic glacial outburst floods that swept across the Columbia Plateau. | |||||
| Kahlotus Ridgetop | Franklin | State | The best remaining example of the Central Palouse Prairie grassland subtheme. | ||||
| 46.89°N -123.05°W | State | A prairie containing unusual soil pimples of black silt-gravel. | |||||
| 47.1086°N -122.7031°W | Federal, state, tribal, private | An unusually fine example of an estuarine ecosystem. Includes Nisqually National Wildlife Refuge. | |||||
| 48.2465°N -124.7002°W | Federal | An outstanding exhibit of sea action in sculpturing a rocky shoreline. A unit of Olympic National Park. | |||||
| Private | The best remaining example of the aspen phase of the hawthorne-cow parsnip habitat type in the Columbia Plateau. Managed by The Nature Conservancy. | ||||||
| 47.825°N -119.3667°W | Federal, state, private | The best examples in the Columbia Plateau of landforms resulting from stagnation and rapid retreat of the ice sheet during the last glaciation. | |||||
| Steptoe and Kamiak Buttes | 47.0325°N -117.2986°W | State, county, private | Isolated mountain peaks of older rock surrounded by basalt, rising above the surrounding lava plateau. | ||||
| 46.85°N -120.5444°W | Federal, state, private | Geologic formation that illustrates the processes of tectonic folding and antecedent stream cutting.[1] | |||||
| 46.0444°N -118.9467°W | Federal, state, county, municipal | The largest and most spectacular of several large water gaps through basalt anticlines in the Columbia River basin. | |||||
| 47.6875°N -119.6247°W | Federal, private | The best examples of drumlins and the most illustrative segment of the only Pleistocene terminal moraine in the Columbia Plateau |