In water the only part of  the electro-magnetic radiation that does not get absorbed is the visible spectrum of light. If water was not transparent to light, thereby absorbing as happens in other wave lengths, we wouldn’t be able to see because the human eye is made to perceive luminous stimuli. 
Sight is the result of a complex process: firstly the image that is projected on the retina is upside down. This image gets converted into nervous impulses and transmitted to the brain and elaborated in various parts of the visual cortex to be reconstructed and interpreted.

The perception of reality depends on two factors: that which is objective as described above and another, instead, subjective as a consequence of aspects due to the memorisation of past events and to personal fantasy and imagination.

The interpretation of the world is a transposition to a different kind of reality: the brain adds, subtracts, re-organises, codifies sensorial information to give an interpretation that is as near as possible to the that of the outside world and the perception we have of it follows fixed rules, for example those theorised in the Gestalt Psychology at the beginning of the Twentieth Century. The image is, therefore, the brain’s interpretation.

But perception may be cheated by ambiguous images, situations and visual tricks: Anamorphous, Ames’ room, pluristable figures, the isomorphism phenomenon, Cornsweet illusion, Kanizsa triangle, impossible objects…
all phenomena that challenge the exactness of human perception. Each image of the project represents one of these phenomena specifically described here: http://www.valentinaghiringhelli.com/edifyng_thoughts_of_a_tobacco_smoker-p13642

Our visual system behaves like a filter: allows only a certain amount and type of information and no other. It’s as if we did not see the world as it is, but through a window: the visual system is our window to the world.

He shows (the brain) that which he wants to and the way he achieves it, because he possesses the essential visual secrets
Charles Patin