NOTE: Watch this tutorial in HD 720p.

http://www.youtube.com/watch?v=DwfqwOiPSRo

[1] Get inside
Enter the Aquatica Research Facility via the elevators.

[2] Documents
Search for the documents in the lower offices or the upper computer stations.

[3] Keycard
Kill the zombie holding the keycard.

[4] Security
Destroy the two security boxes inside the lower level security room.

[5] Lab
Enter the Laboratory on the lower levels and destroy the armored door using the explosive barrels.

[6] Get the item
Retrieve the item from inside of the debris.

[7] Escape
Leave the Aquatica Research Facility via first floor front doors and board the boat to safety.