Subris has two forms. The first is a normal Salthide, albeit covered in barnacles and kelp. The second is similar, except that his legs are replaced by the tail of a whale. He is usually in the second form when in his realm, but takes the first when out of water.
His realm is, as you could guess, full of water. There is a shining light coming from somewhere above though, illuminating the crystal clear water to reveal the soft sand below.