Likeable alphabet book themed around ocean science. There were a couple of terms in here I didn't know - like varve, which refers to the layers of material that get deposited, in much the same manner as tree rings, onto the bottom of a harbour or lake. I'm making a note of that here so I can go look it up in the future, because I find tree rings fascinating things, and varve sounds just as interesting. I'm sure there's a story in it!