Answer:
Who keeps the ocean clean?
So simple, that I can only point. Yet I guide men all over the world.
The warmer I am, the fresher I am. What am I?
There's not a kingdom on the earth I haven't traveled over and over and though I know not whence my birth yet when I come you know my roar. I through the town do take my flight and through the fields and meadows green and whether it be day or night I neither am nor can be seen.
I am the home for feathery animals.
It flows out of the soil, It burns you if it boils, And holds us in its coils, More valuable than gold, As black as it is old.