# Deep calls to deep at the noise of your waterfalls
The word "deep" refers to deep waters, which here are likely the streams rushing down Mount Hermon. The writer speaks of them as if they are people calling out to one another as they hear the sound of their own descent from the mountain.
# all your waves ... have gone over me
The author speaks of his great misfortune and sadness as if they are deep waters that drown him with one wave after another.
# your waves and your billows
"all of your great waves"