Darwin Pano

why is it so dark in the middle?

Looks a bit like it was stitched together - maybe? could be wrong

This and the Mono Lake pano are fine compositions, but they do look stitched in an obvious way.

It also looks like there was a polarizer used, so if you ever wondered why polarizers aren't recommended for wide shots, this is a good illustration. Once you're using a lens wider than about 28mm on a 35mm camera or if you're trying to do a multi-shot panorama, there's no way to get even polarization across the whole frame with a landscape where there's lots of open sky. That's why it's dark in the middle.