Why does it say that the land was established on seas and rivers?
Rashi, Radak (from Bava Basra 74b): Seven seas surround Eretz Yisrael (Tiveryah, Sedom, Chilas, Chilta, Sivki, Aspamya and Yam ha'Gadol) and four rivers - Yarden, Yarmuch, Karmiyon and Pugah.
Radak: It was established near 1 seas and rivers for the needs of the creations on it. However, this mountain is not for all - it is only for "Neki Chapayim
Radak: Al means near, like "v'Alav Mate Menasheh" (Bamidbar 2:20). There is no settled [l'Chatchilah 18 days journey from the sea. The moisture benefits the creations, and also rivers do - Lo "Lasheves Yetzarah" (Yeshayah 45:18). Initially the land was under the water. Water surrounded it on every side, like air surrounds water on every side, and fire surrounds air on every side. Hashem did so and changed it, to show that all is in His hands, and He changes it as He desires.
