Hidden bonuses: 4
Mission walkthrough: Start off by moving forward. Climb on top of a nearby object and you'll find yourself standing next to the first bonus item. Lower yourself using the rope and start swinging in order to catch this object while you're still in the air. I would recommend that you wait with this jump until a small earthquake has ended, so you won't lose balance and fall.
Keep going straight until you get to a relatively large crater. Proceed to your left and make sure to avoid radiation. Eventually you'll find the second bonus item. Head on to your right. Don't forget to use the hook to move freely, but be careful not to fall. Attach yourself to the train tracks and you'll be allowed to collect the third bonus item.
You may proceed to the next section. Use the bionic arm frequently, so it won't take a lot of time for you to reach other areas. You'll soon encounter a small group of enemy guards and it would be a good idea to complete some of the basic combat challenges while trying to get rid of them.
Make sure it's safe and get on top of a large metal structure located in front of the tunnel. Grab the metal pole and start swinging in order to land on a small platform. You'll have to be very precise, because otherwise you'll fail. You should also know that you can't use the buildings to get there. Take the fourth bonus item and use the tunnel to leave this area.