水魔 these days is generally used (semi-)metaphorically to refer to disastrous floods, though originally it is used to describe "water demons" or "water monsters" that caused such floods. I suppose "Leviathan" is a good enough analog.
Edit: Poor Mr. Fishy.
Updated
This is for Z'Gok!
This is for Capule!Think it's best you stop going to that awful place.This is for Acguy!
And this—
FWOOSHSHSHHH—
za‑SPLOOSH!
shpikkle
SKGLOOOOORP
Aaaaiieeeeee!
RUMBLE RROWRFAGLORKKZAWOOSH
Aaaaaack!
That thing is dangerous!This one is for Hygogg!No, bury the whole spring!
Raging Leviathan:
SHAMBLO!
"Written as "raging water/flood monster", pronounced "Shamblo".