The first 3.6 miles are through Pine forest and so not too bad. At the end of that you'll be at the saddle (11,800 feet) that either takes you to Humphrey's or Agazzis Peak (12,356 feet).
To Humphrey's from the saddle it is essentially just 1 mile and only (ha!) 800 feet left, but I tell you it was one of the hardest things I've done in my life as you are essentially climbing up the side of a slightly gravelly mountain top. There is a trail, but it is steep and you're above the tree line, which pretty much ends at the saddle.
In fact I got so tired that I stopped for about 15 minutes before I had reached the top and I thought I was done. I wasn't even going to summit, and everyone kept telling me how close I was, but I didn't want to listen. After the rest, I actually got up to go back down, but then thought "let's just do it!" and so it was only about 10 more minutes and I was at the summit - whew! I took the requisite photos and reveled in my victory for a bit with some fellow hikers and then back down I went.
It was hard as I was fighting nausea on the way down until I had gotten below about 11,000 feet as a guess.
I've been back once, but only to the saddle, but I'll probably do it again in the future. My problem is that I don't eat enough during a really long hike like that and so I need to get better at eating and keeping my energy up.
By the way, both times I've gone have been in June, which is probably the best month to hike because the monsoon hasn't started yet (it starts in July) and most of the snow should be melted by then and the weather should be just perfect! The first time was in 2008 and the second I think was two years ago in 2012.
Kilimanjaro sounds crazy! 19,340 feet! Yikes! That is up there! Good luck with preparing for that one as that sounds incredibly difficult!
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