Research Base - The Road through the Forest (Part 1)

After using climbing arrows to scale the wall from the previous area...

...you'll enter this new section of forest. There's one man standing directly ahead with his back toward you. Don't shoot him yet, since his buddy is just out of sight to his right. Instead, sneak forward and take cover behind the small boulder.

Then activate Survival Instinct and watch the men as they walk away. As soon as the guy on the left turns from red to yellow, indicating that the other man can't see him...

...take him out with a silent headshot.

Now work your way around to the right, following behind the second man.

Either scramble up on top of the large, flat rock, or climb the tree and jump from there to the rock.

From here you can see several more enemies. Two men—the one you just followed and another guy—are standing directly in front of your rock. Three more soldiers are stationed a just down the path. (The remaining men are farther ahead. You can't see them from here.)

If you don't want a full-fledged firefight, start by shooting an arrow into the rock wall off to the right to draw one of the men away.

As he goes to investigate the noise...

...shoot another arrow into the wall a little bit farther to the right, so he'll move out of the other guy's line of sight.

He's wearing a helmet, so you can't kill him with a headshot, so use a poison arrow.

Then take out his companion with a headshot or a stealth attack from above.