seed: Isle

that's Isle as in isle with a capital "i"
it has every boss relatively within a good distance to spawn that gives purpose to sailing at the swamp level, (it's not far just around Moders Island,) and then Moder has an Island has an entire mountain with all the necessities for defeating Moder, (the island is just a massive mountain to the southwest of spawn across the sea a little bit,) and the trader has the ability to spawn in 3 different locations really close to the spawn, one of which is preferred.

you can enter the seed into the world generator to get a look at it as well if you want.