“Zebulun will dwell at the shore of the sea,
And he will be for a haven for ships,
And his flanks will reach towards Zidon.”
Having moved into prophetic mode Jacob now seems more inspired. It seems probable that Zebulun has revealed a liking for the sea and has taken an interest in ships. For the family tribe will have had constant contact with merchants who may have stimulated such an interest, and his residence in Egypt may have brought him in contact with the ships and sailors that had become his passion. This may be why Jacob forecasts such a continuing interest for him and his seed. (This would be an unusual interest in Canaan where harbours were both small and a rarity because of the coastline, which was not suited for shipping, but is understandable in Egypt).
There is no reason indeed why, with Joseph's endorsement, he should not be engaging in some kind of activity in shipping, and this may be what Jacob is referring to. It would not need to be very large to excite Jacob.
“His flanks will reach towards Sidon.” This may refer to some proposed maritime activity aiming to trade with Sidon, a well known merchant seaport in Phoenicia.
The prophecy may include the thought that his descendants too would take up their residence by the sea and would provide harbours for the use of ships with their ‘sides' or boundaries reaching towards Sidon. Assuming that Phoenician Sidon is meant, this last may simply indicate desire rather than fulfilment. As Sidon was famous for its maritime adventures so will Zebulun reach out to emulate them. But there is nothing in the tribe's actual future as recorded in Scripture to suggest this. In the blessing of Moses Zebulun, with Issachar, will ‘suck the abundance of the seas and the hidden treasures of the sands' (Deuteronomy 33:19),' but that simply refers to a fishing industry. (It does however connect them to the sea).
Alternately ‘the sea' may reflect the Sea of Galilee, but the mention of Sidon is against this, and besides originally Zebulun territory did not even touch on that. But the migrations of tribes were not unusual (compare Issachar and Dan (Judges 18)) and some may possibly have moved there.
At first Zebulun in fact resided in the area around ‘Aijalon in the land of Zebulun' (Judges 12:11) in a broad wedge in Southern Galilee between Asher and Naphtali (Joshua 18:10-16), well away from the sea. The River Kishon formed one of its boundaries. (Later Nazareth would be in the territory). Historically, however, there are suggestions that the tribe of Zebulun may later have resided by the sea in the region of the modern port of Haifa.
So the blessing of Zebulun appears to relate very much to the time in Egypt where he would have such opportunities with regard to the sea, and not directly to the future of the tribe.