Adonis Luxury Resort
An Important Note About Collectibles: Unlike in the first BioShock, in BioShock 2 you cannot return to a level once you have passed it. This means you must collect every Audio Diary, Gene Tonic, and use any weapon upgrade stations in the level before continuing on to the next, otherwise they will be forever lost to you on your current save file. To protect yourself, save your game often, preferably creating a separate save file at the start (or end) of each level.
Also note that unlocking the “Rapture Historian” Xbox 360 achievement or PlayStation 3 trophy requires collecting only 100 audio diaries. There are 128 audio diaries total, so don't fret if you miss a few.
Goal: Find a Way Out of Here
After the opening cutscene, head up the stairs in front of you and make your way to the covered doorway at the other end of the walkway. Hold RT/R2 to spin your Drill. Use the Drill to remove the coral covering the doorway. Continue forward, click the Left Stick to crouch and move past the collapsed column. Move forward and into the next area.
That's you on the left!
There is one Audio Diary (Attention: Workers!) in the first room of the Adonis Baths area. It is on the pillar base at the northeast corner of the room, in front of the sparking generator. Continue to the doorway at the east end of the room. Through the doorway, wait for the Leadhead Splicer to appear and mangle him with your Drill.
There's an Audio Diary (Fitness) to grab before moving on. At the bottom of the steps, turn right and you'll come to a locked door. The Keypad code is written on the other side of the steamed door. The code is 1540. Enter the code into the Keypad and collect the diary, Drill Fuel, and money inside.
Once you have the audio log, exit the steam room and continue through the doorway at the other end of the corridor. Move through this next room and exit through the doorway at the other end. The Electro Bolt Tonic is attached to the Gatherer's Garden machine in the next room. Take the Plasmid to gain the Electro Bolt power. With this, you can jumpstart the sparking generator in the pool room.
Take the Electro Bolt Plasmid from the Gatherer's Garden in Plasmid Therapy.
When the Big Sister makes off with the Little Sister, head back to the door you used to enter this room. It is now closed, but can be opened with Electro Bolt. Take aim at the sparking Door Control panel and press the LT/L2 button to use Electro Bolt to open the door.
There are two Splicers in the pool room. Use Electro Bolt to stun the Thuggish Splicer standing across from the doorway, then move in and finish him with your Drill. Be ready for the second Thuggish Splicer, who will come at you from the side. When both Splicers are dead, throw an Electro Bolt at the highlighted panel in front of the generator to restore power.
Goal: Find Tenenbaum
Continue through the doorway along the south end of the room. There is an Audio Diary (To My Daughter) in the Dames room. Upon entering the hallway, take a right and look for the diary by the collapsed locker and flowing water.
After collecting the diary, continue down the corridor to a Securis door. When the door opens, throw an Electro Bolt into the water to shock the two wading Splicers. There's another Audio Diary (Return) here. From the Securis door you used to enter the room, turn right and look for the diary on one of the benches there, below the poster.
Use Electro Bolt to fry the Splicers standing in the pool of water.
Exit through one of the doorways at the east end of the room. Pick up the highlighted Rivet Gun jamming the Securis door. Search the Rosie corpse to collect additional Rivets. When the door opens, kill both Splicers with the Rivet Gun before entering. Upon entering the room, turn right and enter the Bathysphere Docking area through the doorway below the “Rapture Metro” sign. Look for an Audio Diary (They Called It Rapture) next to the suitcase across from the doorway. If you continue to the right, you'll find another Rivet Gun with plenty of ammo. Loot the suitcases and corpses here as well to gather additional items.
When you have the diary and ammo, return to the previous room and head up the steps to the Securis door. Approach the Little Sister in the Grand Foyer to trigger an event.
Big Sister dismounts, landing in the middle of a large puddle of water. You know what to do. Throw an Electro Bolt into the puddle to stun her, then take aim and fill her head with Rivets. She'll remain stunned for all of two seconds. When she is able to move again, she'll likely come charging. Step to the side to avoid taking damage.
Throw an Electro Bolt at the water while Big Sister is standing in it to temporarily stun her.
Big Sister is much faster than you are, and her attacks -- especially her melee attacks -- are quite damaging. If need be, press Right on the D-pad to use a First Aid Kit to restore health (provided you have one, of course), but try your best to avoid her attacks by circling around the statue in the middle of the area. Keep the statue between you and her to shield yourself from her projectiles.
Scaring off the Big Sister doesn't require much. Shock her with an Electro Bolt while she's standing in water a couple of times and hit her with a few Rivets and she will quickly retreat.
Big Sister Fight in the Grand Foyer
After facing the Big Sister, look for an Audio Diary (Generation) on the counter in front of the Vita-Chamber at the east end of the room. After collecting the diary, exit using the door the Big Sister broke through and make your way into the next room. The Big Sister appears, slicing open the window at the far end of the room, letting in the ocean and submerging you in the process.
As a Big Daddy, you are able to survive underwater indefinitely. Exit the building and begin walking along the ocean floor. There's an Audio Diary (Escape From Rapture) to collect right at the start. Look along the left side of the bath for a crashed bathysphere. It's right before the collapsed pillar you have to jump over. Search the Corpse inside the bathysphere to find the diary.
Follow the straightforward path and you'll soon come to a cliff. Drop down and continue moving along until you reach an Airlock chamber. Cycle the Airlock Control to drain the water and complete the level.