Loveday Alexander in Acts in Its Ancient Literary Context (2005) says:
The predominance of the Ionian mental map and the centrality of the sea for the voyages of Greek romance throw into relief the rather different geographical perspectives of Acts. Luke’s story really has two mental maps, one centred on Jerusalem and one on the Mediterranean, and the movement from one to the other enables us to chart a profound cultural shift within early Christianity (79).
I would add that this reflects the tension between the question of the Apostles in Acts 1:6 (“Is it at this time you are restoring the kingdom to Israel?”) and Jesus’ answer in Acts 1:7-8 (roughly: “It’s not for you to know…you will be witnesses from Jerusalem to the remotest parts of the earth”).