What if Cressa-la hadn't touched the water?
How drastically different would things have been?
The Earth has become warmer, making these islands habitable. The humans that survive through Mother Nature's fury have created Tribes, created rules. One of these rules is to not go near the water, to not touch it.
And Cressa-la doesn't. Because she chose to follow the rules, could there be an even bigger consequence than when she had?