3 actual useful places you can dig a canal!

[frail siren]

seed is "marina" spawn island has an interior lake system, and is close enough to easily dig a space bring a karve through. the amogus continent to the north also has two useful spots, one on the lower-middle that lets you through without having to sail around the southern peninsula, and one that lets you get access to the massive lake (not really useful, but would be cool visually)

here's the connecting area by the spawn island, and the two spots in the plains, all low enough to dig through, certainly for a longship and i'd be willing to bet you could barely squeeze a drakar through the area in that third image with enough trial and error

other cool advantages:

• all the traders are nearby (hildir and bogw both on the amogus, haldor just to the right of them)
• the nearby continents have absurd amounts of dungeons, as the swamp to the right has 21 crypts and the mistlands to the left has 17 infested mines.
• bonemass and yagluth nearby, and queen only a slight sail further from where moder is
• a lot of the continents have mountains that are both tall enough and close enough for cape shenanigans (berzerkir heavy or catapult)
• wide open ocean to the south of the amogus if you want to farm serpents
• the big plains on the amogus has like 20 different tar pits lol