Here in Chapter 3, we see that Simon has found a secret part of the forest. We don't know how he found it or what it means. No one else on the island knows about it. When I read this, it really stuck out to me.
"Simon paused. He looked over his shoulder as Jack had done at the close ways behind him and glanced swiftly round to confirm that he was utterly alone."Page 56
I think it means that Simon is hiding something. Maybe he has a mental illness that is making him imagine things. Because if it wasn't this, how have the other boys not have found it yet? I think this moment is important because Simon is a mysterious character in general, so if we figure out the significance of the hidden forest, it could show a lot about his character.