# Where's the furthest you can see from ground to ground? **URL:** \ **Category:** Factual Questions\ **Created:** [September 27, 2007, 6:22pm UTC](https://boards.straightdope.com/t/wheres-the-furthest-you-can-see-from-ground-to-ground/420711 "2007-09-27T18:22:21Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![zyzzyva](https://avatars.discourse-cdn.com/v4/letter/z/b77776/32.png) [@zyzzyva](https://boards.straightdope.com/u/zyzzyva)\ **Post date:** [September 27, 2007, 6:22pm UTC](https://boards.straightdope.com/t/wheres-the-furthest-you-can-see-from-ground-to-ground/420711/1 "2007-09-27T18:22:21Z")
While reading [this thread](http://boards.straightdope.com/sdmb/showthread.php?t=438015) 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](http://en.wikipedia.org/wiki/Mount_Diablo), a distance of roughly 175 miles. Anything higher? ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [September 27, 2007, 6:33pm UTC](https://boards.straightdope.com/t/wheres-the-furthest-you-can-see-from-ground-to-ground/420711/2 "2007-09-27T18:33:19Z")
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](http://www.viewfinderpanoramas.org/panoramas.html) (near the bottom, section “Longest lines of sight”) … > [@](#): > > The true longest possible line of sight based on normal refraction was researched by Xavier Eguskitza of Bilbao, and he found the line of sight between Cerro Paramillo (Colombia, N 7°06’12" W 75°58’09") and the Sierra Nevada de Santa Marta, 483km (300 miles) to the north east. > > …but longer lines of sight than the above are theoretically possible. From the west of Paramillo, there is a 491km view from Altos de Tres Morros, and from the south, there is a 500km view from Paramo Santa Ines (W 75°41’33" N 6°46’22"). In perfect visibility, Pico Ojeda (503km) would be visible through binoculars; and with a telescope part of the ridge further east could be visible at 506km. But I doubt is anyone will ever see this for real. 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](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. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [September 27, 2007, 6:38pm UTC](https://boards.straightdope.com/t/wheres-the-furthest-you-can-see-from-ground-to-ground/420711/3 "2007-09-27T18:38:21Z")
Even with the humble elevations of the UK, you can see [over 100 miles](http://www.viewfinderpanoramas.org/gallery/gb/scafell.html) when the conditions are right. Cool. The longest _photographed_ line of sight on there seems to be [Denali from Mt Sanford](http://www.viewfinderpanoramas.org/gallery/usa/sanford.html). 227 miles, and it’s pretty darn hazy! ---
**Author:** ![zyzzyva](https://avatars.discourse-cdn.com/v4/letter/z/b77776/32.png) [@zyzzyva](https://boards.straightdope.com/u/zyzzyva)\ **Post date:** [September 27, 2007, 7:01pm UTC](https://boards.straightdope.com/t/wheres-the-furthest-you-can-see-from-ground-to-ground/420711/4 "2007-09-27T19:01:05Z")
Great site! Thanks for the link.