Audio Diary #1 – “Alone at Last”
Walk through the first door of this level and the audio diary is immediately to your left.
Audio Diary #2 – “Agnus Dei”
Pretty sure you won’t miss this one. It’s the password from Gil Alexander that you use to progress through the level.
Audio Diary #3 – “Means of Control”
After “Alex the Great” prevents you from accessing the security office, a door will open behind you leading to the rest of the level. The audio diary is on a couch immediately upon entering this door, to the right of the “Fired” corpse hanging from the wall.
Audio Diary #4 – “Prototype”
When you’re first entering the Plasmid Showroom (Fontaine’s Plasmid Spectacular Theatre), you can look through a hole in the wall and see a corpse tied to a chair with a code written in blood. Access that area and you’ll find the audio diary.
Audio Diary #5 – “Life After Sisterhood”
On the second floor of Fontaine Futuristics Tower. You’ll notice it next to the Little Sister vent as soon as you climb the central stairs.
Audio Diary #6 – “A New Cognitive Model”
In the Plasmid Presentation Room with the voice recording of the doctor talking to the patient. To get inside, go to the second floor and look for a hole torn in the wall. Crawl through, follow the passage and drop into the presentation room.
Audio Diary #7 – “Source of Volunteers”
Head to the Marketing Department of Fontaine Futuristics – the area with the Splicer board meeting that comes to life. The room to the left of this area is flooded with electrified water. The audio diary is on one of the submerged desks.
Audio Diary #8 – “Goodbye to Fontaine”
Inside the Office of Frank Fontaine. Turn the boar head to reveal a hidden safe, as well as this audio diary.
Audio Diary #9 – “Abort the Experiment”
After shutting down security and entering the Plasmid Laboratory, this table with an audio diary and Big Daddy helmet will be immediately upon your left. If you enter another underwater section, you’ve gone too far.
Audio Diary #10 – “Solving for X”
Under one of the circuit breakers you use to restore power in Gil Alexander’s giant tank room.
Audio Diary #11 – “Gil’s Place in the Plan”
Next to the Gatherer’s Garden in Gil Alexander’s giant tank room.
Audio Diary #12 – “Outlived Usefulness”
“Pacification Chamber” side of the laboratory. On the control deck of the observation room.
Audio Diary #13 – “Goodbye, Dr. Alexander”
“Holding Cells” side of the laboratory. Below one of the Little Sister vents… on your map, it’s the left vent in this area.
Audio Diary #14 – “Big Sister”
“Holding Cells” side of the laboratory. Next to the Power to the People weapon upgrade station in the locked Surveillance Office.
Audio Diary #15 – “Betrayal”
“Holding Cells” side of the laboratory. Below your feet in the Live Test Facility is a hallway full of prison cells. The northwestern cell (when looking at the map) contains the audio diary, but is also frozen shut. Go through the back of the northeastern cell and Incinerate the ice through the bars.
Audio Diary #16 – “Meltzer’s Choice”
“Holding Cells” side of the laboratory. When you kill the Big Daddy in this area, make sure to search his corpse carefully. There’s an audio diary with a nasty surprise.
Audio Diary #17 – “The People’s Daughter”
Use the genetic key at the Oxy-Fill station to open the entrance to Lamb’s hideout. The audio diary is in the hallway leading to the level-ending elevator.