Answer:
You heart it speak, for it has a hard tongue. But it cannot breathe, for it has not a lung.
The more holes you cover the lower it goes.
Upon me you can tread, though softly under cover. And I will take you places, that you have yet to discover. I'm high, and I'm low, though flat in the middle. And though a joy to the children, adults think of me little.
It is the great nemesis of the lactose intolerant.
Salty water everywhere but not sea in sight.
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?