I'd argue that Golding's presentation of the natural world and the island in this novel is always cleverly balanced between presenting a hot, sumptuous, Edenic paradise - and somewhere that foreshadows and reflects the evil which takes place there. Have a look at this paragraph from the first page of the novel:
All round him the long scar smashed into the jungle was a bath of heat. He was clambering heavily among the creepers and broken trunks when a bird, a vision of red and yellow, flashed upwards with a witch-like cry; and this cry was
echoed by another.
The heat of the island is oppressive and dangerous as well as being fantastically pleasant. It's a 'bath' of heat, but that's juxtaposed with the painful-sounding 'scar' which is 'smashed' into the jungle.
Moreover, the simile 'witch-like cry' creates an odd sense of horror and fear, even though we haven't got into the novel itself yet. Already, in the cries of the birds, there seems to be something forbidding.
This pattern repeats throughout the novel. Look at this section from later:
Then he leapt back on the terrace, pulled off his shirt, and stood there among the skull-like coconuts with green shadows from the palms and the forest sliding over his skin. He undid the snake-clasp of his belt, lugged off his shorts and pants, and stood there naked, looking at the dazzling beach and the water.
Again, see how Golding works? Positive: 'dazzling beach' and 'water'. Negative, obviously is the 'skull-like' coconuts. And then you have these 'green shadows... sliding over his skin', which seem both natural and luxurious, and lurid and scary.
You find examples like this throughout the book - Golding is a master at balancing the exotic glamour with a strange sense of foreboding and danger.
Hope it helps!