How does it indicate that? The skull is in the background and the focus objects are in the foreground, it's something called perspective, but even still, the skull absolutely dwarfs those things that are around a kilometer tall.
I'm really not understanding how you came to that conclusion... you see that ship I circled in the below image? That ship is almost as tall as a football field is wide, sixty meters.
Oh I didn't see the ships. Though I wouldn't scale them as large as you did, but rather Sunny like. Where do the 60m come from?
If you start scaling from those ships I agree - Onigashima is much bigger than I said earlier.
But the overall scaling in the image doesn't fit still.
See the stairs below onigashima? Normal sized humans would need ladders to climb them up. They'd be at leat 4-5m high. If the ship's 60m long, the stairs must be even taller. Maybe 15-20m. It's ridiculous.
I think, at least regarding this pic, we can say it's very inaccurate scaling.
The crew reached the core of Onigashima very quickly. The battlefields were very close.
Egghead has shittons of infrastructure including public transportation, something Onigashima lacked entirely. You could walk your way everywhere you wanted.