1. From the propaganda poster’s location, jump down to the stream and follow the path leading to the secondary objective marker. You'll find corpses along the way. A blackbox is found nearby.
2. After checking out the secondary mission, proceed to the main mission objective. Follow the cavern until you reach the shallow river. Take the path to the right and follow it. Open your nanovision to locate the second blackbox and a nanosuit upgrade module by taking the narrow path to the right.
Blackbox #03-02 and Nanosuit upgrade
3. Continue until you reach the base. From the main entrance, go all the way to the left to find a drainage pit with an open tunnel. Enter the tunnel and you'll find a corpse shortly. The blackbox is found there.