Haleakala is the world's largest dormant volcano, with the crater measuring some 7.5 miles long and 2.5 miles wide.
We are at nearly 10,000 feet above sea level here, having climbed from sea level (by bus)
You can't get the depth perception from a picture. It's from 1,400 to 3,000 feet deep in there.
You can see the crater only about 20% of the time because of cloud cover. We were quite lucky today.
There's only 75% of sea-level oxygen levels in the air up here. You could feel it, too. Just walking was a chore.

More on Haleakala and Maui here: http://www.haleakala.national-park.com/info.htm#geo