Audio Diary #1 – “Eleanor’s Progress”
This one’s hard to miss. It’s part of the “We Will Be Reborn” candle altar as you make your from the train station into the park.
Audio Diary #2 – “The Old Sheepdog”
In the security basement, immediately before you remote hack through a broken window to gain access to the park ticket.
Audio Diary #3 – “Volunteer”
The middle of the Rapture Museum, beneath a bench that is directly between the doors to the Gift Shop and to the Hall of Future.
Audio Diary #4 – “Eat Dog”
Can’t miss this one. It’s in the same gift wagon as the Drill Power tonic Eleanor leaves for you.
Audio Diary #5 – “’Child’ and Guardian”
Located near the far windows of the El Dorado Lounge, where you fight your first Big Daddy.
Audio Diary #6 – “You, Me, and 1959”
Before entering the Journey to the Surface ride, head to the Ride Maintenance room on the left for this audio diary.
Audio Diary #7 – “Escape Plan”
On floor next to the second harvest corpse.
Audio Diary #8 – “Lamb the Problem, Sinclair the Solution”
Across from the last audio diary is a pile of crates with an Eve Hypo, .50 Caliber Rounds and another audio diary. It’s right behind some falling water, and also near a large neon arrow sign that says “Conformity & Co.”
Audio Diary #9 – “Truth is in the Body”
This one’s well hidden. Near “Chaos Corner” and just a bit before the second Andrew Ryan robot is a stairway leading to a series of balconies overlooking the track. Diary is on a workbench between two of those balconies. If you reach the Scientist and Artist animatronic dioramas, you’ve passed the staircase and should go back.
Audio Diary #10 – “Deterioration”
To the right of the animatronic scene with the parents and child is a storage room full of giant hands. Climb the one in the center as if it were a ramp and you’ll find the audio diary on an upper balcony. (Thanks to reader “EngieIndeed”)
Audio Diary #11 – “Working for Sinclair”
Past the animatronic scene with the parents and child watching television is a water-filled room with a Power to the People weapon upgrade station. In a room to the right is an ammunition vending machine and the audio diary.
Audio Diary #12 – “Doctor Lamb”
Near the end of Journey to the Surface, under a security camera, is a Ride Maintenance passage with a Bot Shutdown panel. Continue in here and to the left to find a door covered in wooden boards. Break the boards with melee to reveal a hidden room with the audio diary.
Audio Diary #13 – “Efficacy”
At the end of Journey to the Surface is a miniature lighthouse scene. The door to your left holds a pile of rubble and an audio diary.
Audio Diary #14 – “Dating Tip”
You might have noticed this door before entering Journey to the Surface. Once you’ve opened / unlocked all maintenance doors in order to exit Journey to the Surface, this door will finally open. Head inside for the audio diary.
Audio Diary #15 – “A Father’s Love”
Halfway through the Hall of the Future, next to a Vita-Chamber.
Audio Diary #16 – “Cutting Corners”
Back of the Gift Shop, near a safe.
Audio Diary #17 – “Rapture is Deliverance”
Restroom of the Gift Shop… “Dames” side. You have to Electro Shock the locked door to enter.
Audio Diary #18 – “Disappeared”
Trapped in ice near the beginning of the level. Once you have the Incinerate plasmid, you can melt the ice and get it.
Audio Diary #19 – “Wooden Nickels”
When Sinclair boards the train, you’ll be attacked by a Splicer swarm. Finish them off, then look for a newly opened door to the left of the previously frozen door. It was locked when you were here before. Inside is an audio diary – make sure to grab before leaving the level.