I tryed seeing what would happen if i just stayed on the island. I had people come FROM the sea with no boats. Just something that would be cool is having raiders come in boats, with defences that can blow up boats or you have to make a sea side defences!
That sounds like a cool idea
i have a small lake on my map... and a incendiary mortar set it on fire xD
either the lake was oil/tar (looked like water tho) or the mortars are made of napalm
back to topic: it's a cool idea, but as so few maps actually have water in them, i don't think it's worth coding
All pawns both friendly and hostile is capable of swimming in "deep water" tiles and shallower. You are suggesting to include vehicles, which some mods manage with debatable results. Whilst I agree that it would be awesome to have pawns charge your island base with boats, I believe it adds little to the game especially since most tiles are either water only or land only.
In order for your suggestion to function properly we'd need:
- New map generation with islands
- Fully implemented working vehicles
- New AI using and understanding vehicles
- Tile based rule restriction for certain vehicles (allow movement on water not land and reversed)
- And more problems that I could not think of atm
All this development could be used for other features which might add more to the game long term. A trick for a good suggestion is something that adds a lot for little time spent, and I believe your suggestion does the opposite. Although the idea of vehicles sounds kinda cool and might be something for a more mature Rimworld.