The door directly in front is sealed shut, but you can jump up and break the vent to go through.
To enter the supplies and armory, head to the side of the entrance room. Flip the switch found there, and run across the center room to reach the door before it closes. You can retrieve armor, health, and a shrinker from both the supplies and armory rooms.
When you're done, flip the switch near your entrance to open the main corridor.
Blue key Edit
The blue key is located in a room overlooking the first section of the main corridor. Enter it, and take the elevator to the control room.
There are laser tripmines behind the door to the second section. While you can run past them before they become primed, you will need to duck under them or destroy them.
While you can enter vents that lead throughout the map, some paths are closed until you unlock the appropriate door.
Red key Edit
When you unlock the blue key door, you will enter a slime room. After collecting both boots and scuba (as required or appropriate), dive into the water, and look at the opposite side of the water for the red key.
At the top of the slime room is an path that leads to the exit via a bridge.
Blast the explosive canisters, and enter the ductwork revealed by the explosion. The ductwork leads behind the blast door - you can either unlock the door or commence the auto-destruct sequence.
<insert tips here>
Other features Edit
<insert other features here>
Level contents Edit
<insert table here>