Olive's Ocean by Kevin Henkes (10+)

Martha didn’t know Olive—not really. But when Olive is killed in a hit-and-run accident, and her mother gives Martha a section from Olive’s journal, Martha knows they could have been friends. Now Martha and her family are going to Cape Cod for the rest of the summer, and Olive, who had always wanted to see the ocean, haunts Martha’s thoughts and dreams. A brilliant, touching coming-of-age story, and a Newbery Honor Book.