This story might be apocryphal; I haven't been able to verify it, but it is certainly plausible.
Mount Egmont National Park forms almost a perfect circle around Mount Taranaki. Given its status, its bush remains intact, unlike the rest of Taranaki. You get a great view of this dark green circle with a mountain poking out of it on a flight from Hamilton to Christchurch, assuming, of course, the weather is good, which is a different matter. Now, I'm told, if you look carefully at a map, you'll see it isn't quite a circle - the boundary has a small kink in it. (I'm not talking about those annoying extra bits that extend west over the Kaitake ranges that detract from the otherwise perfect cone-shape - it's the circular bit I'm refering to.)