Answer:
Where humans breathe liquid.
The day is their night and the night is their day, when I shout and they shout back I run away.
What is always on its way but never arrives?
In many hallways you would stand, if not with this in hand.
What falls down but never gets hurt?
How did the farmer find his wife?
Easy
Animal
Difficult
Food
Funny
Kids
Logic
What am I?