There are around 72 total items including random Medals in Hydrophobia: Prophecy but your concern should be documents and objects. Since collecting all documents and objects scattered throughout the game will unlock your Private Eye achievement or trophy.
We have listed down every document and object that you can find in the game in order so you can keep track of all the collectibles and revisit certain chapter if you miss anything.
Hydrophobia Private Eye Achievement/Trophy Guide
Below are all the locations of the objects and documents that you can find in Hydrophobia.
Act 1 (Kate’s Apartment)
Briefing Location. You’ll get this at the start
Sleeping Pills Location. Look at the table, in front of the couch.
Classical Engineering Location. Near the arm-chair which is next to the couch.
Certificate of Achievement Location. It is at the red table (1st floor).
Sponsorship Location. It is also at the red table (1st floor).
Weighted Wrist Bands Location. At the arm-chair (1st floor).
Hand Grips Location. You’ll get it right next to the couch.
Checking In Location. Same as the Hand Grips spot.
Roy the Donkey Location. It’s on the shelf.
Briefing Location. It is next to Yate’s dead body.
Queen of the world Replica Location. Look at the desk which is next to the exit door (left).
A vision of the future Location. At the same spot, on the floor.
Review Location. Look at the desk which is next to the exit door. (Right)
Queen of the World Anniversary Location. You will jump into the metal beam right after the explosion; you’ll have to go right for the story to continue.Before moving right look for a metal pipe right in the front of you, so you can take a jump from it and swing to the next metal floor to get this!
Distribution Centre Alpha
Queen of the world anniversary guide Location. There is a ladder in the room, climb up to it and find it.
Upper Security Complex and Security Office
Malthus Opens the Debate Location. Right after you’ll leave the elevator’s shaft, you’ll see a dead body. Look on its left.
Epitaph Location. You’ll now see some climbable bars, climb and you’ll get to it.
Wanted: MilaCrass Location. It is on the table.
Interrogation Location. You’ll see this on the floor.
10th Anniversary Commemorative Coin Location. It is on the desk of the room where you found the first frequency key.
Honesty Corner Location. It is on a desk, in the room with Billingham.
Commanders Cut Location. It’s at the end of the same room.
Morton, Sitrep, Coming Storm Location. Once you’ll collect the Billingham’s character profile from the desk you will get all of these.
Death or Glory: Malthusians vscornucopians (D) Location. After the elevator has fallen behind Kate, go to the Elevator Shaft and into the secret room. Look at the dead body and you will get the Explorer Medal and the Collector Medal if you have not missed any other collectibles.
Elevator Shaft (Act 2)
Settling In Location. Swim to the elevator shaft and you will notice a door. Prepare for a long swim through the door into the hallway to reach this document. Look for a room with an air pocket to the left of the corridor if you need air.
It is rewarded if you collect all the collectibles in one breath.
Cycloconverters Operational Overview Location. Look at the desk of the same room
Anxiety Location. It’s next to the blue lockers, on the high area. This is only unlocked once you have completed the Cycloconverters B, so you’ll have to come back.
Maintenance (Act 3)
Anxiety No More Location. It is right on the floor where the gas ceiling is leaked and is between the two fires.
Resistance Location. You’ll see a dead body when you’ll exit the vent, this is on it.
VFD Power Control
VFD Facility Overview Location. It’s on the floor, same room where you hack the control systems.
Loading Bay Servers
The Prophecy of Malthus Location. Look underwater in the yellow rails corner.
Launching Mankind’s Great Hope Location. Swim into the flooded corridor right after you have distinguished the fire by opening the door, search at the yellow container.
You will now be awarded the “Collector 2” medal ONLY if you have collected all of the items.
Power Cell Access
From the Flames Location. Once you’re done with the electrified wires, you’ll enter into a doorway, turn left from there and then take another right into another corridor. At the right side there are some breakable windows – The item is behind those on a machine.
Maintenance Alpha Location. Follow the last route and instead of going left (into the 2nd corridor), go straight and you’ll see another breakable window. Look at the blue machine of that room.
Queen of the World Anniversary Flag Location. You’ll kill some Malthusians after you’ll get out of the elevator; there is a bench on your right. Look at it.
Official Anniversary Big Boy Band Location. On the bench of the third walkway (corner).
Official Anniversary Big Boy Hat Location. Go straight from the Third Walkway and look for an Eat Stop, and search behind it.
Satisfaction Location. Look at the bench of the 4th walkway.
If you find anything missing, you can comment and I will add it up.