I tried the summit of Mt Ruapehu here in NZ and got 358.8 km to Mt Owen. Not bad as I was expecting Tapuae-o-Uenuku which is a little shorter at 342 km.

One advantage in NZ is that on a nice day you actually have a good chance of seeing it.

Oh ... clicking on Mt Owen doesn't return the favour ... or the other nearest peaks. But Culliford Hill does show a return back to Ruapehu, 355.4 km. Clicking on Tapuae-o-Uenuku also, as expected, gives a line to Ruapehu: 342.3km.

Mt Cook is high, but has too many other high peaks near it.

Mt Taranaki is isolated, but doesn't turn up any very long distances.

I don't expect any other candidates in NZ.

Update: actual and accidental photo of Tapuae-o-Uenuku from Ruapehu (342 km), seven months ago.

https://www.reddit.com/r/newzealand/comments/1m9p0bh/tapuaeo...

And, as pointed out in a comment, also Mount Alarm 2.5 km further.

What is the longest in North America? Or Europe proper -- not Elbrus (which I've not been to but have been close enough to see, from several places e.g. from a house in Lermontov (~94 km only), summit of Beshtau (93 km), Dombai ski field (~63 km), somewhere on A157 (~50km).

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tombh 11 hours ago | parent | next [-]

Wow, glad you had fun exploring. It suddenly made me think of a little feature that I'm not sure we made the best job of exposing. In the little trophy icon toggle on the right, there's the Top Ten list of views, then under those there's a little line that just says "In current viewport: 123km". Did you see that? Did it make sense? I implemented it, so of course I know that it's better than clicking all the points around a peak to find the longest view from a mountain summit. But maybe it's not obvious to other users? What I do is zoom in so that the viewport only contains the area of the summit (or indeed entire country for that matter) that I'm interested in, then I look at that "In current viewport:" line without having to click anything.

So using that, I would say that the longest line of sight in North America is from Mount Rainier, at 390km, looking North West into Canada: https://map.alltheviews.world/longest/-121.76853942871094_46...

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brucehoult 11 hours ago | parent [-]

Oh, I missed that!

That gives a longest in NZ of 365.3 km from Ruapehu, skirting past close by Tapuae-o-Uenuku (in the Inland Kaikoura Range) to a point on the Seaward Kaikoura Range near the peak of Manakau. Clicking on the actual Manakau peak also gives 365.3 km back to Ruapehu.

I can't seem to find a peak to get a reverse path back to Mt Ranier. Everything I try gets stuck in the Olympic Peninsular. (I was there once ... 1998 or so ... a place called Hurricane Ridge IIRC)

	▲	tombh 11 hours ago \| parent [-]
		Right, I think we need to make that "In current viewport" thing more prominent somehow. So this is the NZ longest line right https://map.alltheviews.world/longest/173.61386108398438_-42... One thing to note about finding reverse lines, is that they're not truly mathematically identical because the observer always has a height of 1.65m and the destination is always some point at the surface, therefore 0.0m. It doesn't always make a difference, but it sometimes can.

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repelsteeltje 12 hours ago | parent | prev [-]

Not a geologist, but interesting that many of these sites are close to equator. Suppose that's where mountains are higher because tectonic plates are more active?

Anyone with expertise want to comment?

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kmaitreys 11 hours ago | parent [-]

Not a geologist either but an astronomer. Never heard that tectonic activity has any association with proximity to equator.

Mountains can rise higher near equator because you have the least gravity there. The whole Earth bulges along the equator. But I don't think it's measurable.

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jmalicki 11 hours ago | parent | next [-]

It's also interesting because the radius of curvature is smaller, meaning the distance to the horizon is shorter north south, and a lot of these views are north south. So the increase in mountain height more than overcomes the other effect!

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rao-v 6 hours ago | parent | next [-]

Are we saying line of sights are not symmetric? Why not?

	▲	jmalicki 6 hours ago \| parent [-]
		The earth is an oblate spheroid to an approximation. It's not that they're not symmetric, but at the equator the north south axis has higher rates of curvature than anywhere else (but the east west has somewhat lower rates because of the larger circumference due to the bulge). So that large lines of sight are near the equator on a north south axis (or symmetrically south north) is crazy because the high rates of curvature in that direction at those latitudes should give the shortest distance to the horizon on earth, making those lines of sight even that much more impressive!

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tombh 11 hours ago | parent | prev [-]

Woah, I've been thinking about this whole project for so long, but never considered that!

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iso1631 11 hours ago | parent | prev [-]

While Everest (8849m) is the highest point above Sea Level, Chimborazo (6267m) in Ecuador is further from the centre of the Earth (about 2000 metres further), due to the equatorial bulge. It's very measurable.

	▲	kmaitreys 8 hours ago \| parent [-]
		Well that's not what the claim and clarification was about. The question was: can a mountain rise higher in the equator as compared to higher latitudes? It is not about highest point from centre of Earth. That's is related to equatorial bulge but irrelevant to the discussion.