There's a very widespread metaphor applied to the Talmud, through which it is likened to a vast body of water, which means that the person "navigating" the Talmud is being likened to a sailor, a swimmer, a diver, or - I suppose - a fish. Where does this metaphor come from?
Job 11:9 refers to "the deep things of God" as being broader than the sea (רחבה מני-ים), but I have never heard anybody refer to the ocean of Torah, midrash, piskei halakha, kabbalah or anything really - save for the Talmud specifically.
When was this beautiful metaphor first used? Can it be found within the Talmud itself?