For the Islands I suspect they will be similar to Sunlit Tides. Where some islands are only accessed by swimming to them, which you could only do once the Seasons patch came out. If you can travel using these boats, like cars then I bet there are docks on each of the island so instead of roads there would be a water transport system.
This EP sounds really interesting, although there just doesn't seem like there is much content in it yet. Although it's only vaguely announced so I can't complain yet.
Wait till winter, my respected western island neighbour, than you could
walk to the nearest island. I did the same with you in real life but you weren't at home so I'll try next year.
I am unsure if this would be possible, but it certainly be fun.
Hack, imagine investing in Titanic size boats, which you can upgrade and rent to the pioneers of Sims towns. That would be a good money dump.
A challenge could be buying out all ships out there, or upgrading a millionaire boat, like my Castle Costalot, but than 'floatable.'