“ The eastern sea ” refers to the Dead Sea, and “the western sea ” to the Mediterranean Sea. Both are used with reference to people.
وَهٰذِهِ ‹ ٱلْمِيَاهُ ٱلْحَيَّةُ › تَرْمُزُ إِلَى تَدَابِيرِ يَهْوَهَ لِلْحَيَاةِ .‏