Mount Campion Caves National Forest. It's on the Mainland and it consists of 10 sims. You can even rent the houses there. When you land there, you can get an info notecard about the park.
I didn't enter the caves because truthfully, I don't like scaring myself and caves are scary, dark and smelly spaces. And this time, my companion is a little King Charles Spaniel from Jian. I did spent an enormous amount of time trekking and I think I walked the same path a few times too.... lost obviously. Thankfully, I can just teleport home without a search party looking out for me.
In this spot where this picture was taken, if you're patient enough, you can even catch a glimpse of a fox running around, but it was too quick to catch for a picture.