Memphis In The Sea?

We are planning on driving to Arizona to spend Christmas vacation with Granna & Papa Rob (Pauls Parents). The boys and I were talking about it and I told them we would probably stop in Memphis Tennesee to see Mamaw on our way. Matthew had a puzzled expression and then said "Memphis in the sea?". I said "no, Memphis Tennesee." Then he said "Oh, I thought Mamaw was out on the water somewhere."