The Underground Berlin | Main missions Wolfenstein: TNO Guide

Once you reach the second grate, you will have to squeeze through

First of all, enter the U-Boat and steer downwards. At the end of the tunnel, you will have to exit the boat and cut through the chain to make it possible for yourself to proceed. Keep along your path until you reach the next passage, where you will have to leave the boat and, next to the statue, to swim past the statue and open the passage at the other side. Now, return to the boat and keep going up, then right and up to resurface.

Rotate the turbine to make the hole get under the surface of the water

Now, you will get into the big hall. You need to find the second tunnel that should be on the opposite wall. After you get to the other side, you will reach a big turbine that you need to rotate. Climb onto the ladder and hold down the lever on top, for as long as it will be possible to get through.

Swim ahead and turn right to come out of water. Climb up the ladder and fill the tank with more water, in order to raise the level, with the lever.

Cut through the suspending chain

Jump into the pool now and swim up to the next platform. Jump over to the next pool and dive. Use the blowtorch to cut through the chain that suspends the naval mine (both of them would be best). Wait for the mine to make the passage and swim in there.

You can see the lift from here

Now, keep going ahead and dive in the big round tank. On the left, there is a rift, which will take you ahead, along the tunnel. After you swim for several meters, resurface an come out of water. Now, keep going ahead until you reach the lift.

The control room, where you need to press the button

Now, keep running ahead, for as long as the officers appear on the radar. Now, go towards them. After you have eliminated them, approach the switch that you fought the Nazis next to, and open the gate ahead. Watch out because there will an armored Nazi run out. It is a good idea to shoot the laser at him but, you need to remember to recharge. After you have finished him off, return to what you were originally doing and run inside. Then, over the stairs into the control room and press the button there. Now you are up for an ordeal. There will appear enemies and three armored ones, yet bigger than usually. It is best to destroy the first one using the laser and take his weapon to finish off the remaining two with that gun. Remember to go for the heads.

After the fighting ends, get into the train and pull the lever to complete this mission.