What is meant by "And the people of the Gulf expected all places were that way..."?

The people of the Gulf expected the nature around them to be deceiving,

Part of the far shore disappeared into a shimmer that looked like water. There was no certainty in seeing, no proof that what you saw was there or was not there. And the people of the Gulf expected all places were that way, and it was not strange to them.

This fits in to the theme of the Pearl looking beautiful but bringing nothing but suffering.