# Where is the longest visible line of sight on Earth from point A to point B?

We've had some interesting questions on being able to see country A from B, and on visibility for miles in every direction.

For a 6 ft tall person, the horizon in a 'flat' area is meant to be about 5km. Obviously the higher you are, the further you can see, if nothing is obscuring your view.

So somewhere on Earth (point A) presumably, you can see all the way, unobscured to Point B, which is further away than any other two visible points on earth.

Where would this line be - that is, between which two points A and B?

• would you be happy to exclude perpetual cloud cover? Jul 27, 2017 at 0:16
• @GayotFow I don't believe there's anywhere with constant cloud on earth, but for the sake of argument, let's assume no cloud. Jul 27, 2017 at 0:21
• "I can see Russia from my house!" Jul 27, 2017 at 1:10

``````COUNTRY    | FROM                          | TO                    | KM. | AZIMUTH
===========|===============================|=======================|=====|========
Kyrgyzstan | Dankova (5.971 m.)            | Hindu Tagh (6.436 m.) | 538 | 170º
Colombia   | P. Cristóbal Colón (5.776 m.) | Alto Mora (3.264 m.)  | 506 | 206º
``````

Longest line of sight seems to be from Dankova to Hindu Tagh, 538 km in Kyrgyzstan. Here's a HeyWhatsThat link to the winning peaks in Kyrgyzstan/China. And another one for the combo in Colombia.

• I was surprised to see that view from Mt Everest is only #8 on that list. Jul 27, 2017 at 14:07
• @PeterM guess it gets obscured by other mountains nearby Jul 27, 2017 at 22:05
• markhorrell.com/blog/2020/… that "Hindu Tagh" name does not seem to exist although the peak does.
– chx
Jul 23, 2021 at 18:57
• @PeterM I'm surprised it's that high. While Everest is very high it's got a whole bunch of other high stuff around it. Jul 24, 2021 at 2:40
• This is a case of "technically correct, but probably not useful". It's rare for the atmosphere to be clear enough to see 300 km/200 miles, and almost unheard-of to be able to see further.
– Mark
Jul 28, 2021 at 2:10