Audio Diary #1 – “A Silent God”
Hanging next to the painting of the first BioShock’s plane crash. On your left as you enter Little Eden Plaza from the airlock.
Audio Diary #2 – “Misbehaving”
The counter of the Poisoned Apple bar in Little Eden Plaza. To get inside, you must climb up any of the nearby staircases and drop through the roof.
Audio Diary #3 – “The Rumbler”
Inside the restroom of the Mermaid Lounge, under a mound of frozen ice.
Audio Diary #4 – “Plasmid Shipment”
On a table in the slot machine room. Upper floor of Mermaid Lounge.
Audio Diary #5 – “Farther to Fall”
Right next to the Mermaid Lounge’s weapon upgrade (Power to the People) station. To access, go upstairs, shoot a hack dart through the bar window to unlock the door and drop through the hole in the floor.
Audio Diary #6 – “’Father Simon Wales’”
In an office on the first floor of the Pink Pearl brothel.
Audio Diary #7 – “Double Standard”
Second floor of the Pink Pearl, in the central room with the bed, dead hooker and purple flickering light.
Audio Diary #8 – “Wales ‘an Wales”
Daniel Wales’s desk on the highest floor of the Pink Pearl. His office is next to the hole in the floor that Daniel drops through.
Audio Diary #9 – “The Date is the Code”
Search Daniel Wales’s corpse after defeating him.
Audio Diary #10 – “Lamb’s Salvation”
Outside the entrance to Plaza Hedone, propped next to the door you’ve spent the first half of this level trying to open.
Audio Diary #11 – “The Pair Bond Mechanism”
In Plaza Hedone, the second shopping center of Siren Alley. Near the door to the Little Sisters Orphanage, as well as a Gatherer’s Garden and security camera.
Audio Diary #12 – “Bury Her Memory”
Second level of Plaza Hedone, in a northwestern room with a desk and a fridge.
Audio Diary #13 – “The Requirements of Utopia”
In the southwest, ground-level corner of Plaza Hedone are two small alleys that meet in a loop. One side of this loop drops down to a watery sewer with a Vending Expert tonic hanging from a noose… and the audio diary right after that.
Audio Diary #14 – “An Empty Niche”
Find the illegal plasmid lab by hitting the “conspicuous switch” at the Green Grocery. At the very back of this area, in a dark room with dead bodies in bathtubs, you’ll find the audio diary on a table.
Audio Diary #15 – “Lamb’s Operation”
Located in the smugglers’ hideout, which is above the Green Grocery, past a turret and through a steel door. Most any walkway on the 2nd or 3rd levels of Plaza Hedone will lead you to this area eventually.
Audio Diary #16 – “My Name is Eleanor”
Last bunk bed in the group sleeping quarters of the Little Sisters Orphanage.
Audio Diary #17 – “Shackled to the Great Chain”
Enter the first part of Pump Control Substation #5. On the upper level, in the northwestern corner, is a locked office. Hack the door through the grate and grab the audio diary.
Audio Diary #18 – “Guidance of Lamb”
At the candle altar, before heading into the “Temple of Lamb.” It’s underneath the paintings of the first BioShock protagonist’s hands.
Audio Diary #19 – “Therapy with Grace 2”
In the last hallway before Father Wales’s church, there’s a door on your left leading to Sofia Lamb’s office and a Power to the People weapon upgrade station. The audio diary is tucked in a filing cabinet.
Audio Diary #20 – “The Creed of the Faithful”
At the main altar of Father Wales’s church, beneath the large painting of the butterfly-headed woman. Grab before the place floods.