There's a place near Mt St Helens called the Ape Caves. They're lava tubes formed long long ago that you can hike through. At times it you're in a large area climbing over rock piles and at other times you're on smooth flat ground in a tight spot.

When I went through it seemed like I was on fire... it was quite a workout.

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Put me on wheels and I'll turn tricks.

Clever? Nah, I ran out of that years ago. But if you find this, let me know, k?
"The road goes ever on..." ~ Tolkien

In memory of my friend skip...
Go then, there are other worlds than these