The wkTerrainSync module, when used with a terrain (not a PNG), supports loading a custom water.dir file. This file not only contains the water animation, but the animations for all objects that sink in the water. They all share a dedicated 32 colour palette. Interestingly there are sprites in the water.dir file that exist but the game doesn't use them. This is why the concrete donkey, homing missile and the mole bomb don't change colour when they enter the water. This should probably be corrected in a future update. It would also be nice to hear a splash sound when the homing missile enters the water, but I'm just nit picking!
The module also supports replacing any sprite within the Gfx0.dir / Gfx1.dir files. These files contain all other sprites in the game, including the worms themselves and their animations.