Is it possible to walk around the entire rim?
They used to allow visitors to hike the trail around the rim and another trail that goes to the crater floor, but they stopped that (I'm not sure how long ago) to preserve the crater from erosion. When it was created it was 700-feet deep. Now it's only 500-feet to the bottom.
The only foot traffic allowed on the crater now is the hourly half-mile tour from the visitor's center to the west side of the crater.



