Answer:
You row in one while you float.
What kind of room doesn't have physical walls?
Two year-old children who throw tantrums get this nickname. So did the tsar "Ivan."
What has many keys but cannot open a single lock or door?
What is used by man, tossed by trees, everywhere but unseen?
I build up castles. I tear down mountains. I make some men blind. I help others to see.