Do not enter where the soldier went in. Go to your right and find an open window. There are three guards inside. You can play cat and mouse with them, but I found it easier to drop them all and move on.
The next section is open and is covered with snipers. Remember, if they see you, freeze in cover until the laser goes away. Follow cover all the way to the left, stick with the fence, and avoid the guard who patrols near you. Look for a pipe going up the first tower you come to, across from where you started. Climb up, and then around the tower, look for more pipes. When you reach the marker, a guard will be on the tower, you’ll probably have to knock him out.
The next section has three sentries between you and the door you need to reach (there’s a guy in there, too) and the lights come on before you get there. I just wound up dropping them all with the stun gun and moving on.
Now that you’re all suited up you have a few more options. In the next room, you can ascend and shimmy around the shelves to stay out of sight. Look for a window between the third and fourth rows of shelves. A guard will patrol back here. Then follow the wall on your left as it curves around, and there are a few guards, including an armored one, between you and the exit. Move fast and quiet.
You start the next section behind a sniper. If you sneak up on him, the other sniper will see you. You can drop off the walkway to your left and move around to drop down, or shoot him with something. There are four sentries patrolling the area below you, and crawlspaces underneath the buildings. You need to grab the edge of a building below the roof and climb around so you can get onto the cages and then onto the second building. There’s a zipline there, but be sure to clear your path with EMP or shock darts before you go for a ride.
Move down the path straight ahead of you. Use your sonar to track and mark the guard dog. You have to hit him first. Then, look for the sniper on the tower beyond your position. Arc a high shot with a sleeping gas arrow into his nest and he’s down. Then it’s just a matter of staying in cover to the waypoint.
Head straight ahead across the road and climb down the cliffs to reach the water. There’s a shimmy/climb path you can follow to Briggs and the boat.