To-day the sea has gone away from it so much that it is nearly high and dry; but four hundred years ago it was quite a seaport, when Spain did not have a great many sea towns on the Atlantic coast.
At the time of Columbus's voyage the king and queen of Spain were angry with the port of Palos for something its people had done that was wrong--just what this was we do not know.

But to punish the town, and because Columbus wished to sail from there, the king and queen ordered that Palos should pay them a fine for their wrong-doing.

And this fine was to lend the king and queen of Spain, for one year, without pay, two sailing vessels of the kind called caravel's, armed and equipped "for the service of the crown"-- that is, for the use of the king and queen of Spain, in the western voyage that Columbus was to make.
When Columbus called together the leading people of Palos to meet him in the church of St.George and hear the royal commands, they came; but at first they did not understand just what they must do.

But when they knew that they must send two of their ships and some of their sailing men on this dreadful voyage far out upon the terrible Sea of Darkness, they were terribly distressed.

Nobody was willing to go.