This Washington State Park Hides a 500-million-year-old Cave That's More Than 2,000 Feet Long

And you can tour the cave for free.

Crawford State Park Heritage Site in Washington, not to be confused with Crawford State Park in Colorado, is just about as far north as you can get without hitting Canada. In fact, the park sits just minutes from the U.S.-Canada border and is relatively small, at just 49 acres. But its small size and northern location do nothing to deter visitors who come from all over the world to see Gardner Cave, a 500-million-year-old limestone cavern that is more than 2,000 feet long and almost 300 feet below the surface of the earth.

This deep geological wonder is only more impressive in person, when you can walk among the stalactites, stalagmites, flowstone, and rimstone pools that cover the floor, ceilings, and walls of the natural limestone cave. It was mapped by the 1911 federal land survey and is one of Washington's longest caves.

Those who make the journey to Crawford State Park Heritage Site, which is, at first glance, a simple day-use park, are in for a treat. There are free cave tours Thursday through Monday at 10 a.m., noon, 2 p.m., and 4 p.m. And while there’s no charge to join a tour, visitors must register online. The guides are well-versed in the wonders of Gardner Cave and will help visitors recognize the many formations found within it — including the towering stalactites and stalagmites.

Popular underground sites include a series of rimstone pools near the back of the cave and the 7.8-ton column (the largest in the Pacific Northwest) that formed when a stalactite merged with a stalagmite.

The ancient cave was formed from a limestone “ooze” created by shells that settled on the floor of the cave millions of years ago. This ooze turned into a metaline limestone rock that was folded on top of itself when mountains formed around 70 million years ago, according to the Crawford State Park Heritage Site cave pamphlet.

The park is open from May to September, weather depending, but Gardner Cave is best visited in the middle of summer, when the cool temperature of the cave — which hovers between 39 and 42 degrees Fahrenheit — provides a cool respite from the heat. The park is closed on Tuesdays and Wednesdays.

To visit Crawford State Park Heritage Site and the Gardner Cave, you’ll need to pick up a Discover Pass, which provides access to all the state-managed lands in Washington. An annual pass is $30 and a day pass is $10. There are also several free days throughout the year, including Earth Day on April 22, Juneteenth on June 19, and Veteran’s Day on November 11.

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