Just going to take a shot in the dark and say you're exploring the field east of the blacksmith/museum where you catch puppyfish?
If you find you can't go further, then you don't have the grampleton fields expansion that's packaged separately from SDVE because it can cause performance issues.
You can find the expansion and instructions on the SDVE nexus page if you look for it.
Although I haven't played since 1.6 dropped, so it's entirely possible I'm wrong and that's just an as-yet unfinished integration of the new update with SDVE.
Edit: For what it's worth, there's nothing particularly interesting about grampleton fields itself, except for being a massive foraging area that npcs don't go to. Maybe good for very late game processing, but not really interesting otherwise.