The Lab
This is where The Particle originated from. It takes three full days to get from the beginning of the forest to the lab by foot (starting from Sam's house), which means you will die if you don't bring or find water.
It's laid out kind of like a college campus. All the subjects are held in one building, testing facilities are in another building, the boss has his own building, and the developmental equipment is in another building.
I'm not going to describe it because it is quite graphic and disturbing.
The Clearing
About a fifteen minute walk into the forest (starting from Sam's house), there is a clearing in the trees. This is where Jay lives when he's not stuck in the lab.
It has a sort of magical atmosphere to it. In the middle of the clearing is a rushing waterfall, the water splashing down into a medium-sized pond at the bottom, which runs into a small stream. The sun always seems to hit the water at just the right angle. The flourishing wildlife around the waterfall adds a few more colors to the mix. In general, it's just a pretty view.
Wolves
Description to be added