This dream really scared me...so naturally I turned to the internet to interpret what awfulness awaits. Turns out going into deep water and dreams of death can represent the subconscious mind and change in life. Plunging into deep water, a storm and all that signifies spirituality and the deeper recesses of one's mind. Death means one is shedding something from the past and transforming or experiencing the "death" of a part of one's self.
Freud, Jung and various dream interpreters would probably all see this a different way with somewhat similar elements. Either way it gave me some comfort.