Oliver and the Seawigs by Philip Reeve and Sarah McIntyre

When Oliver’s explorer parents go missing, he sets sail to find them with some new friends. There’s a grumpy albatross, a nearsighted mermaid . . . even a living island! But the high seas are more exciting and strange than Oliver could have imagined. Can he and his crew spar with sarcastic seaweed, outrun an army of sea monkeys, win a fabulous maritime fashion contest, and defeat a wicked sea captain in time to save Mom and Dad?