The island on which the Tyre of Alexander's day had been built was about half a mile from the shore. The water between was about eighteen feet deep, and formed a harbor for the vessels. The great business of the Tyrians was commerce. They bought and sold merchandise in all the ports of the Mediterranean Sea, and transported it by their merchant vessels to and fro. They had also fleets of war galleys, which they used to protect their interests on the high seas, and in the various ports which their merchant vessels visited. They were thus wealthy and powerful, and yet they lived shut up upon their little island, and were almost entirely independent of the main-land.