I had to think for awhile on this one.... it was making me laugh too much. :)
I think I would be a watering hose. Stupid - I know.
My reasoning is this...... because a hose is used to bring water and help with things. The water can make plants grow, rejuvinate thirsty animals, cool everyone off, and be something that can be an instant game on a hot day.
So - helpful, refreshing, playful........ how's that for DEEP? :)