What does this comparison tell you?

Question

A gull patrolling between the wave crests of the desolate sea will dip to catch a fish, and douse his wings; no higher above the whitecaps Hermes flew

Answer 1

How high above the surface of the ocean was the gull flying?

Now read the part after the semicolon.

Let us know what you think.

Answer 2

I got it thank you very much :)

Answer 3

You're welcome.