Water interrupts my optic flow

As it is summertime I make my way to the beach as often as I can and, while there, I often go into the water to cool off. Upon leaving the water, however, I have noticed something interesting as I walk back towards my beach chair. As I make my way up the beach I tend to look down at the water and feel myself being slightly off keel or off balance. It is as though my walking is slightly interrupted or altered as the water creeps up the shoreline in front of me and then back out into the ocean. While I have attributed part of this to some water in my ear, where part of one's balance is derived from, the study of perception offers another explanation. Below is a video showing the waves I am referring to.

According to the ecological approach to perception an optic flow, the movement of everything within a scene relative to the observer, is one source of information for which one gains knowledge about what is 'out there' or in the world. As one moves and the rest of the world is stationary there is a global optic flow which sends a visual signal, one source of information, to the brain that tells it that the observer is moving while the world is not. Now, as the water moves up the beach, past myself walking, and back down to the ocean it sends contradictory signals to my brain, thus explaining the off balance feeling. My brain believes that everything should be stationary, while water occasionally moves, in a different direction, thus sending my brain mixed signals about my own movement and the optic array, structure created by the surfaces, textures, and contours of the environment, around me.