Moomin and the New Friend by Tove Jansson
When Moomintroll and Sniff find a message in a bottle down on the shore, it leads to an expedition to Lonely Island on a little raft. High winds and a storm at sea nearly lead to disaster but they are rescued by a new friend, the ever-resourceful Too-Ticky. Moomintroll's close friend, Snorkmaiden, is jealous but she soon learns that finding a new friend doesn't mean losing an old one. A magical picture book about the Moomins based on the art and characters created by Tove Jansson.