Unfortunately, this is officially designated as a cheat by the game developers.
Some years ago I released wkAwesome, one of its features was hiding the water waves, as well as sprites, the game HUD (timer, wind, chat bars, etc.), the landscape, and disabling the background redrawing (the "awesome" effect). However, I quickly removed it because the water feature was cheating, and because I did not properly set up compatibility. It wasn't for general use anyway, so it remains in some hidden forum on TUS. I might update it later for the general public if necessary.