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Crush Depth
Use the elevator to go down.
Enter the level B lab.
A scientist has trapped himself underwater to escape some aliens.
Kill the aliens and press the yellow button to teleport the scientist back.
Press E for him to follow you.
Go to the retinal scanner and he will open it for you.
A bullsquid is in this corridor.
This retinal scanner is broken and will not open the door. Instead go back to the corridor where you killed the bullsquid.
Climb up the ladder that is in the middle aquarium.
The vent space up here is crawling with fast aliens in the dark. Use your nightvision to spot them more easily.
When you manage to kill all the aliens enter a smaller vent at the end.
Drop down from the vent and enter the teleport on the right.
Press the buttons and you will be teleported in a few seconds.
Enter the next area through here.
Some alien zombies will attack you in this tight corridor.
Enter another vent.
Climb up the ladder.
Some zombies roam around down here.
Go down this ladder.
Turn the wheel to open the gate. This will release two marine aliens out in the open.
Get back to the big aquarium. You will have to prepare to swim fast and enter the gate you opened with the wheel. The two aliens will be very hard to kill so it's best to try to avoid them.
Go through here and don't look back.
At the end you will find a valve that will close the gates before the aliens can come to you.
Wait for the water to drain.
An X-Ray is working here.
You can't pass before the X-Ray is disabled. Shoot the cracked box at the end of the corridor to turn the power off.
Enter the airlock.
Press the button to cycle the airlock.
Jump in the teleport.
Jump in the teleport you find in Xen.
Cycle the airlock.
Jump in the water here.
Swim through the broken glass.
Swim up the drain.
Continue through the corridor.
More Half-Life: Opposing Force Walkthroughs
This Half-Life: Opposing Force walkthrough is divided into 12 total pages.