When I said jumping underwater to get rid of minions, I meant that you can choose not to equip them underwater as a method of disposal or changing your build in that environment. I really, really, hate uncontrolled aggro in a three dimensional environment. We also can't use marks or wells to heal minions underwater. How do you heal them there?
I honestly am altogether terrible at my necro underwater: none of my skills, weapons, and traits function there, and I haven't found a way to adapt yet. It doesn't help me any that there's different Death Shroud skills there, too.