Where's the furthest you can see from ground to ground?

Factual Questions
1

While reading this thread about visibility from the WTC observation deck, I started wondering about this. I’ve read that Mt. Kilimanjaro offers the greatest viewshed, or visible area, but this isn’t the same as the greatest distance. There might be somewhere else where you can see some visible object that’s further than anything visible from Kilimanjaro.

I figure it must be some mountain that’s not surrounded by other tall mountains and that’s within a couple hundred miles from more tall mountains. I know on a clear day, you can see Mt. Lassen from the top of Mt. Diablo, a distance of roughly 175 miles. Anything higher?

2

Well, from near the top of Mt Kenya I have seen the summit of Kilimanjaro, a straight-line distance of almost exactly 200 miles according to Google Maps.

According to this page (near the bottom, section “Longest lines of sight”) …

The site has some cool “virtual panoramas” showing what you could see if you had perfect visibility.
E.g. http://www.viewfinderpanoramas.org/gallery/USA/whitney.html

compares a photo from Mt Whitney to the virtual view, proving a 190-mile line of sight.

3

Even with the humble elevations of the UK, you can see over 100 miles when the conditions are right. Cool.

The longest photographed line of sight on there seems to be Denali from Mt Sanford. 227 miles, and it’s pretty darn hazy!

4

Great site! Thanks for the link.