Flaming Geyser State Park, Natural park in Black Diamond, United States.

Flaming Geyser State Park is a nature reserve in Black Diamond that spans roughly 480 acres along the Green River. The area offers riverbank access, forest trails, and two geological formations with bubbling effects where methane from underground chambers rises through water.

Coal prospectors drilling in the early 1900s struck a methane pocket 1,000 feet down, sending gas, saltwater and flames 25 feet into the air. The site was run privately from the 1920s until the 1960s, when the operation went bankrupt. Facing home development, Washington State Parks bought the land and has managed it since.

The park's name comes from a flame that once burned in a concrete basin, fed by methane from a pocket 1,000 feet below ground. The nearby Bubbling Geyser still seeps gas through a mud hole. A local legend credits miner Eugene Lawson with trying to profit from the ignited gas, though records of his involvement are sparse.

The park covers 503 acres with over 3 miles of Green River shoreline; the ADA-accessible Salmon Interpretative Trail explains the river's steelhead and salmon ecology. Summer tubing and rafting draw most visitors, and a designated field is set aside for remote-controlled model airplanes. The flaming geyser has not been lit since 2016, so expect the concrete basin and the nearby Bubbling Geyser mud hole rather than flames.

The geysers form from a rare geological condition where methane from coal seams naturally pushes to the surface and creates bubbles in water basins. This is not like traditional thermal geysers but rather a cold gas phenomenon that only a handful of places on Earth share.