Here’s a classic problem my dad tried to explain to me when I was ten. I didn’t understand what he was saying, but to my credit I was at least getting pretty damn close to being potty trained by then.
Superman is thirsty. He is flying above a lake, and he has a really long straw. He dips one end of the straw down to the lake and puts the other end in his mouth. How close to the surface must he get in order to drink? Remember he has superlungs.