1. Wail you ships of Tarshish!" (1-14)
Phoenicia (Tyre and Sidon) was proud, as a bestower of crowns, rich with trade to Tarshish, Cyprus and Egypt. Yet these places would all wail and mourn, as the Lord planned to bring down the fortresses of Tyre and Sidon. He would remove their pride and humble all who are renowned on the earth, using Assyria as His instrument. Babylon as well is an example (13). This is God's character: He opposes the proud but lifts up the humble (1Pe 5:5b).
2. Her earnings will be set apart for the Lord (15-18)
For seventy years the cities of Tyre and Sidon disappeared, with no profit or earnings from trade. Yet after humbling them so long, God would bring them back. They would return to their ways of prostitution by trade. But God would use their profit and earnings for his own purposes. It may refer to their resources contributing to the rebuild of the temple (Ezra 3:7).