Ape Cave
The longest lava tube in the continental United States, formed by an eruption roughly two millennia ago beneath what is now Mount St. Helens country.
DocumentedReservation requiredFee or pass1 to 4 hoursChecked July 2026
Pacific Northwest and California · 7 field files
Current field files in Washington.
The Atlas is curated, not exhaustive. These are the sourced files in Washington in Volume 01, each with its own access status, evidence label, and check date. Nothing here is statewide travel advice.
- Category coverage
- Public-access summary
- Ape Cave: Seasonal, timed entry. Bigfoot of Washington: Regional folklore file; public trailheads only. Fort Worden Batteries: State park. Georgetown Steam Plant: Scheduled open houses. Maryhill Stonehenge: Daily, 7 a.m. to dusk. Northern State Recreation Area: Public trails, dawn to dusk. Seattle Underground: Guided tour only.
- Last content review
- Catalog reviewed July 2026. Each file carries its own source-check date. Conditions change; check the primary source before traveling.
Field files
Bigfoot of Washington
Washington's forests sit at the center of a long-running Bigfoot tradition, with modern reports describing a tall, hair-covered figure moving upright.
Folklore + reportsPublicFree1 to 3 hoursChecked July 2026Fort Worden Batteries
Concrete gun batteries, dark corridors, and empty emplacements built to guard the entrance to Puget Sound from the late 1890s onward.
DocumentedPublicFee or pass2 to 5 hoursChecked July 2026Georgetown Steam Plant
A 1906 industrial cathedral of turbines, catwalks, brick, and steel that helped prove steam power could feed a fast-growing city.
DocumentedScheduled daysFree1 to 2 hoursChecked July 2026Maryhill Stonehenge
A full-scale concrete Stonehenge replica completed in 1929 as a memorial to Klickitat County service members killed in World War I.
DocumentedPublicFree45 to 90 minutesChecked July 2026Northern State Recreation Area
A 726-acre public recreation area on part of the former Northern State Hospital farm, with 1921 dairy-barn ruins overlooking the meadows.
DocumentedPublicFree1 to 3 hoursChecked July 2026Seattle Underground
Buried storefronts and sidewalks left below Pioneer Square after Seattle rebuilt above its old street level following the Great Fire of 1889.
DocumentedGuided onlyTicketed75 minutesChecked July 2026
Curated routes through Washington
Across the line
Files in other states within 200 straight-line miles of a Washington file. Distances are not drive distances.
Stone House, Witch's Castle
A roofless stone park shelter hidden in a forest ravine, widely nicknamed the Witch's Castle despite its much less supernatural origin.
History + folklorePublicFree1 to 2 hoursChecked July 2026Fort Stevens + Peter Iredale
A former coastal-defense fort paired with the rusting remains of the Peter Iredale shipwreck on the edge of the Graveyard of the Pacific.
DocumentedPublicCheck the source2 to 5 hoursChecked July 2026OSH Museum of Mental Health
A museum inside the Oregon State Hospital's Kirkbride Building that confronts the institution's history and the changing treatment of mental illness.
DocumentedTicketedFee or pass1 to 2 hoursChecked July 2026Pendleton Underground
A guided route through spaces beneath downtown Pendleton, presented by a nonprofit tour organization founded in 1989.
History + folkloreReservation requiredTicketedAbout 90 minutesChecked July 2026
Official sources used in Washington
- US Forest Servicefs.usda.gov , opens government source in a new tab
- Washington State Military Departmentmil.wa.gov , opens government source in a new tab
- Washington State Parksparks.wa.gov , opens government source in a new tab
- Seattle City Lightseattle.gov , opens government source in a new tab
- Maryhill Museum of Artmaryhillmuseum.org , opens institutional source in a new tab
- Skagit County Parksskagitcounty.net , opens government source in a new tab
- Bill Speidel's Underground Tourundergroundtour.com , opens official site operator in a new tab
Also in Pacific Northwest and California: California, Oregon.