Natural Camouflage

From BioShock Wiki

Natural Camouflage is a physical tonic which renders the user invisible as long as they remain stationary. You must not be firing or taking pictures. If an enemy is attacking you it will not work. If an enemy walks into you they will notice you. Very useful for outlasting security alarms, lying in wait to eliminate a splicer, shooting a bouncer then disappearing,reloading, boss fights, etc. Great for laying proximity mines in front of a big daddy, since they turn aggressive towards you if they step on one, but if you're invisible, they rampage for a bit then calm down.

Game Caption

Need some peace and quiet? Splice in Natural Camouflage, stop moving, and just fade away. Remember, not seeing is believing!

Location

Research Level 2 with Houdini Splicers.