water/splash effect over an existing tattoo

I was just wondering if its possible for an artist to do the water/splash/wave effect (not sure of the proper wording) over an existing tattoo or would it be difficult? Thanks

Without actually seeing the tattoo, it's hard to tell, is there a pic of the tattoo online such as myspace or anywhere we can see the existing tattoo? Also, if you go to a competent artist, they could give you some better insight by seeing the tattoo in person. Post a pic and we can hopefully get you started in the right direction at the least.