Originally posted by i have 2024 vision fear me:

It's best to get a boat and sail around the coasts of black forest biomes. That said, it's not guaranteed. ...

Agree. This is my approach ... usually before taking on the Elder, I start sailing the coastlines looking for (a) Haldor and (b) potential swamp locations. I usually find Haldor before I find a good swamp location. Often I find Haldor somewhere near the Elder.

That said, occasionally have resorted to looking at the map generator and found it was one of those maps where all of his spawn locations were near the edge of the world.