I have an idea... please vote its good or very bad idea?!
When you move into water(tile)
your character will look like as you swimming..
and if you click right mouse button your character will be under water(tile) and nobody can't kill you with weapon..
but you only can be under water for 30 or other second..(average time under water)
and you can buy breathing apparatus, so you can be under water for more time..