Zidon. Was a seaport. the mother city of Phoenicia, the granary of Egypt's harvests. The Zidonians had built Tyre on a rocky island, and connected it with the mainland.
I travail not = I have not travailed. The verbs which follow in Isa_23:4 are in the past tense. The sea speaks to the mother Zidon: thou seekest Tyre thou findest only the sea.