I went as far north as I could in a half day and then came back.
First, north is mostly swampy areas and big bay-like areas. I suspect the whole area north of me is a giant bay, but lacking a boat, did not manage to explore very well.
(Why do I not have a boat? Because the zombies can swim. And if I’m caught out in the middle of the night climbing a tree is a safer option than being in a boat.)
Second, I saw about 20 cows, 1 punk-ass child zombie that pelted me with eggs, another gazillion duckens, 5 fish, and a pig I might go back for tomorrow.