Midrash su Salmi 24:2

When R. Dimi came from Palestine, he said in the name of R. Jonathan, what is the meaning of the passage (Ps. 24, 2) For upon seas he hath founded it, and upon rivers he hath established it? i.e. the seven seas and four rivers which surround the land of Israel (Palestine), the seven seas are the seas of Tiberia, Sodom, Chirat, Chiltha, Sipchi, Aspamia, and the ocean; and the four rivers are Jordan, Jarmuch, Kirumyun, and Phiga." When R. Dimi came, he said in the name of R. Jonathan: "In the future the angel Gabriel (Fol. 75) will go hunting for the leviathan, as it is said (Job 40, 25) Canst thou draw out the crocodile (leviathan) with a fishhook or cause his tongue to sink into the baited rope? And if not for the help of the Holy One, praised be He! he would not conquer him, as it is said (Ib.) He is the first in rank … he that hath made him can alone bring his sword near to him." When R. Dimi came, he said also in the name of R. Jochanan: "When the leviathan becomes hungry, he expels from his mouth a gas which makes all the waters in the deep boil, as it is said (Ib. 41, 23) He maketh the deep to boil like a pot. And should he put his head in paradise, not one of the creatures could withstand the bad smell of the gas, as it is said (Ib.) He maketh the sea like a seething mixture. And when he gets thirsty, he makes the sea hollow like beds, as it is said: Behind him he causeth his pathway to shine." And R. Acha b. Jacob said: "The deep does not come to its natural way before seventy years, as it is said (Ib.) Men esteem the deep to be hoary — and hoary is not less than seventy years."