Visit to Jerusalem. Paul probably sailed in a ship specially chartered to convey Jews to Palestine to keep the Passover.
Related Commentaries of Acts 18:19
Acts 18:19-22
19 And he came to Ephesus, and left them there: but he himself entered into the synagogue, and reasoned with the Jews.
20 When they desired him to tarry longer time with them, he consented not;
21 But bade them farewell, saying, I must by all means keep this feast that cometh in Jerusalem: but I will return again unto you, if God will. And he sailed from Ephesus.
22 And when he had landed at Caesarea, and gone up, and saluted the church, he went down to Antioch.