Originally posted by knighttemplar1960:

Its random. The farther away you get from your start location the more likely you'll have the more difficult biomes present. If you want to build a coastal swamp base you can drop a workbench and flatten the terrain to get rid of some of the swamp water.

okay then my world seed is really bad for iron because none of the close to the center swamps have crypts even tho the swamps are medium size and not that far from the center all the swamps have plains surrounding the swamps. Like this seed has the longest swamp I have ever seen and even that swamp is surrounded by plains. But that island is quite far.

Are the wraiths and overall swamp mobs a pain in the ass if you make a swamp base?