Lot of good natural history. Basically everything east of the cascades use to be a giant rainforest 3.5 million years ago. 12,000 years ago it was all glaciers that formed the gorge, grand coulee and ancient lakes (picture Niagara Falls but dried up now). Seriously so much cool wonder out in eastern Washington being from western Washington I thought it was all desert. There’s little nuggets of history everywhere. Here check out this website of top 100 natural sites in Washington. It was made by the Washington Geological Society. I recently moved to eastern Washington and I’ve visited almost every place now

https://wa100.dnr.wa.gov/