At this town of Acanthus Xerxes commanded the fleet that it should sail through the trench by Mount Athos and should await his coming at Therma; but he himself led his army through the land of Pæonia. Here the camels that carried the victuals for the host were set upon by lions, which coming by night from their dens touched neither man nor beast, but the camels only; but what it was that drave them to this, considering that they had never before seen the beast, or made any trial of it, no man can say. There are many lions in this country, and wild oxen also with very long horns, which are brought into Greece. So Xerxes came to Therma; and being at Therma he saw the two mountains Olympus and Ossa, which are indeed marvelously high. And when he heard that there was between these mountains a narrow pass through which ran a river, and that this was the road into Thessaly, he conceived a desire to go on shipboard and see the place where the river flowed into the sea. Wherefore he embarked on a ship of Sidon, the same that he was wont to use when he would go on such a journey, and gave the signal for the others to set sail also. And when he came to the place, he marveled much at the outflow of the rivers, and calling to him the guide would fain know whether it were possible to bring the rivers into the sea by any other way.
Men say that in old time Thessaly was a great lake, being shut in on every side by high mountains. And indeed toward the east Ossa and Pelion are joined together at the base, and on the north is Olympus, and on the west Pindus, and on the south Othrys. In this land there are many rivers which all make their way into the sea by one channel, even the Peneus. But they say that in old time this channel was not, but that afterward Poseidon made it; which may well be if Poseidon brings earthquakes to pass, and if chasms are his handiwork. For it is manifest that the hills have been torn asunder by an earthquake. When therefore Xerxes asked the guides whether the water could pass by any other outlet into the sea, the men, as knowing the nature of the place, made answer, “There is no other way, O King, by which this water can pass into the sea save this which thou now seest; for Thessaly is girded about with hills.”