Why are there sometimes "waves" in the sandy floor near the beach, inside the shallow water?

Question

Why are there sometimes "waves" in the sandy floor near the beach, inside the shallow water?

Answer 1

it is what the sea has done with it's wave like motion it moves the sand and eventually it creates the "waves" as you put the deep tide mark doesn't have the same marking because as the tide going back out levels the sand back flat

Answer 2

it is caused by the motion of water (waves) over the sand.  

very detailed info here:

http://cwp.library.ucla.edu/articles/ayr...

Answer 3

Those waves are made because the tide goes up and down the shore all day, and the waves push the sand to give it a ripple look