As the old adage says, "water and electricity do not mix" because in real life water has impurities that make it super conductible. So, what would happen in D & D if, for example, a sorceress would throw a shocking grip on a creature underwater?
Would not the spell work? Would it also affect the pitcher? Would it spread out and hit everything underwater?
Shocking grip on particular species that "You have an advantage if the target is wearing a metal armor", which indicates that they take into account their conductivity.
What about Call Lightning or Chain Lightning, if casting a top level spell would change the result?