I think it was with a mouse. It was a watercolor type animation. This mouse is trying to find someone, like his father or something. The scene I remember the most, I think was at the bottom of the ocean or some body of water and the mouse saw a tin can with a picture on it, within another picture and so on. Then it moves in through each picture.

An American Tail (1986) (http://amazon.imdb.com/title/tt0090633/)

The Secret of NIMH (1982) (http://amazon.imdb.com/title/tt0084649/)

The Mouse and His Child (1977) (http://www.imdb.com/title/tt0076416/)