Adam Clarke on Jonah 1:3

To flee unto Tarshish - Some say Tartessus, in Spain, near the straits of Gibraltar, others, Tarsus, in Cilicia; and others, Taprobana, or the island of Ceylon, formerly called Taprobah; and Tabrobavagh in Sanscrit, to the present day.

And went down to Joppa - This place is celebrated as that where Andromeda, daughter of Cepheus, was chained to a rock, and exposed to be devoured by a sea-monster, from which she was delivered by the valor of Perseus. It is the nearest port to Jerusalem on that side of the Mediterranean.

And he found a ship - The Phoenicians carried on a considerable trade with Tartessus, Eze 27:12; and it was probably in one of their ships that Jonah embarked.

He paid the fare thereof - He paid for his passage. This shows that there was traffic between the two places, and that each passenger paid a stated fare.

From the presence of the Lord - He considered that God was peculiarly resident in Judea; and if he got out of that land, the Lord would most probably appoint another prophet to carry the message; for Jonah appears to have considered the enterprise as difficult and dangerous, and therefore wished to avoid it.