Further into the lower levels, you'll encounter a heavy security door requiring a keycard. This keycard is located in the old security office. From the drained corridor, proceed through the newly accessible path. You'll enter a series of interconnected storage rooms. Be wary, as this area often features your first encounter with a 'Crawler' type enemy; use stealth or evasion if possible. In the third storage room, you'll find a desk with a broken computer terminal. On the desk, partially hidden under some papers, is the Security Keycard. Pick it up. As you do, a loud bang might occur, signaling a nearby enemy. Be prepared to move quickly back to the security door and use the keycard to proceed.
