Batman Arkham Knight has 315 Riddler Collectibles in total (179 Trophies, 40 Riddles, 6 Bomb Rioters, 90 Breakable Objects).
Find all of their locations to complete Riddler's challenges and to lock him up in GCPD. This will earn you the "Riddle Me That" achievement. It's also required for 100% game completion and to initiate the full Knightfall Protocol.

NOTE: Please note that all 90 breakable objects together count only as 18 of the 243 Riddler challenges (every fifth one counts as one complete challenge).


Bleake Island = 37 Trophies, 11 Riddles, 3 Bomb Rioters, 15 Breakable Objects
Miagani Island = 38 Trophies, 10 Riddles, 3 Bomb Rioters, 15 Breakable Objects
Founders' Island = 41 Trophies, 10, Riddles, 0 Bomb Rioters , 15 Breakable Objects
Stagg Enterprises Airships = 21 Trophies, 3 Riddles, 0 Bomb Rioters, 15 Breakable Objects
Panessa Studios = 21 Trophies, 3 Riddles, 0 Bomb Rioters, 15 Breakable Objects
Arkham Knight HQ = 21 Trophies, 3 Riddles, 0 Bomb Rioters, 15 Breakable Objects

NOTE: You can keep track of your progress in the Riddle Section of your world map. There you can see which objects you have found in each area.

It's recommended that you beat the story first before collecting anything! This is to ensure that you have all the required gadgets and can access all areas.

There are 37 Riddler Trophies on Bleake Island.
https://www.youtube.com/watch?v=Rx50Lvg8F5U

There are 11 Riddles on Bleake Island.
https://www.youtube.com/watch?v=NIkdNRt80V0

There are 3 Riddler Bomb Rioters on Bleake Island.
https://www.youtube.com/watch?v=3IfLZ2p2p2s

There are 15 Breakable Objects on Bleake Island.
https://www.youtube.com/watch?v=uv1m2W3wvrU

There are 38 Riddler Trophies on Miagani Island.
https://www.youtube.com/watch?v=-_Qca6yZi8U

There are 10 Riddles on Miagani Island.
https://www.youtube.com/watch?v=IFbRDmCB_lI

There are 3 Riddler Bomb Rioters on Miagani Island.
https://www.youtube.com/watch?v=5DsuBqiWZRs

There are 15 Breakable Objects on Miagani Island.
https://www.youtube.com/watch?v=wnAqnUY7xQA

There are 41 Riddler Trophies on Bleake Island.
https://www.youtube.com/watch?v=uMs_MRNtqE0

There are 10 Riddles on Bleake Island.
https://www.youtube.com/watch?v=jVlGJAt5Y-0

There are 15 Breakable Objects on Bleake Island.
https://www.youtube.com/watch?v=xgycJNqr5iA

There are 21 Riddler Trophies on Bleake Island.
https://www.youtube.com/watch?v=vg0rOopoQb8

There are 3 Riddles on Bleake Island.
https://www.youtube.com/watch?v=AaiJXaKkU1o

There are 15 Breakable Objects on Bleake Island.
https://www.youtube.com/watch?v=_v8FCDARKSk

There are 21 Riddler Trophies on Bleake Island.
https://www.youtube.com/watch?v=2ruQC3woRcg

There are 3 Riddles on Bleake Island.
https://www.youtube.com/watch?v=SkCsIA2o3h8

There are 15 Breakable Objects on Bleake Island.
https://www.youtube.com/watch?v=WcUGc5-4Qz0

There are 21 Riddler Trophies on Bleake Island.
https://www.youtube.com/watch?v=hZrJ8J1zNkQ

There are 3 Riddles on Bleake Island.
https://www.youtube.com/watch?v=WyGSkHb9lYc

There are 15 Breakable Objects on Bleake Island.
https://www.youtube.com/watch?v=zexTcqqHH_M

The Freeze Blast is the only Gadget in Batman Arkham Knight that you won't get through natural progression. Unlike other gadgets you actually have to find and pick this one up yourself. The Freeze Blast can be found in Panessa Studios in the room after exiting the elevator.

It is required to get some of the Riddler Trophies! Thus it's required to complete the game 100% and to get the full Knightfall ending. As the name suggests you can freeze enemies with it to render them immobile for a short time, making it useful for combat encounters. You can also freeze steam pipes with it to reach certain riddler collectibles that are otherwise inaccessible. See end of video for a short demonstration of this tool.

https://www.youtube.com/watch?v=em8ltzYpny4

https://www.youtube.com/watch?v=OaVoKAMXKl4