Pause the game, highlight the "Map" option, then hold Right + L2 + R2 + Circle + Square + X (simultaneously). Then, enter the options screen and choose the "Cheats" selection
Submitted by Jamin Truman
Pause the game. Highlight weaponry, hold L2+select+circle+square+X (simultaneously). If done correctly you should hear a sound. Then go to options and select "cheats"
Submitted by Jimmy Nguyen
At the first level at the beginning (where gabe parachuts) aim the parachute to the rock where the gi is sitting then hit down to get air, you should get on top of the rock where a chest and a h11 are waiting!!!
Submitted by georgeschicker
Finish the C-130 wreck site and unlock characters from the original Syhon Filter
Submitted by Nick Entwisle