I’ve always had an affinity with water. I love the Lake District and the Scottish lochs and there is a very nice body of water near me with dog walks, wooded walks etc with it. I also love looking at the sea on a long beach walk. I’ve sometimes seen seals off the Scottish coast but it’s the sense of eternity (of the sea going on and on on and on) that I find peaceful and relaxing.
Witches of course are notorious for not liking to cross water but what about your other characters, fairy tale or otherwise? How do they relate to water? Do they indulge in water sports or is swimming left strictly to the merpeople?(!). Populations need water supplies to be able to survive so how does your fictional universe arrange this? Do people gather their own water as sadly so many people in the developing world still have to do or is plumbing as developed as our own or better?
Do water borne diseases exist here ? If water is not the fluid needed for survival on your world, what is? And what will your world do to ensure it has the supplies it needs?