The Sea of Tranquility - I blew through this novel from my YA summer reading list, even though it's almost 400 pages. If you loved Eleanor & Park, it's not a read-alike, but the two stories have enough in common to make this a safe bet.
A Hole in the Bottom of the Sea Song with lively animation and ocean life. Great for summer or ocean themes. Also good for teaching fluency in reading. Recommended by Charlotte's Clips http://pinterest.com/kindkids/sensual-science-charlotte-s-clips/