What are the furthest distances you can see from particular viewpoints on Planet Earth, and how far in miles?

Question

I mean looking at other parts of the earth, NOT into space. thanks

Answer 1

There is a formula to calculate the line of site and it is:-

                  

1.25x square root of h1+h2 = Nautical miles          

Where:-

H1 is the sea level height in feet of the observation point.

H2 is the sea level height in feet of the observed point.

It is a very rough guide but it gives you an Idea of the maximum distances.

Answer 2

On the ocean, it is about 12 miles.  The higher in elevation you are, the farther you can see.  Some points here in Colorado, on a clear day I can see a mountain range that is 100 miles away.