The Island is seen as a microcosm of the world (this means the world in miniature)
There is the good side of the island where Ralph leads (this is where the beach is and the landscape is pleasant to reflect the sense of calm and order of Ralph’s leadership style.
There is the mountain where the dead parachutist is found. This is a mysterious and unpleasant place. This is where the fire is made to attract any possible rescuers.
Castle Rock is where Jack’s tribe live later in the novel. It is an unforgiving landscape and presented as difficult to reach and unpleasant, reflecting Jack’s evil nature.
The other side of the island is rocky and covered by trees, making it unfriendly and forbidding to the boys.
The sea is vast and shows how cut off they are from the rest of the world.