It's sink or swim for Jack and Annie when the Magic Tree House whisks them off to the middle of the ocean. Luckily, they find a mini-submarine on a coral reef. Unluckily, they are about to meet a giant octopus and one very hungry shark. Will the dolphins save the day? Or are Jack and Annie doomed to be dinner?

Did you know that there's a Magic Tree House book for every kid?

Magic Tree House: Adventures with Jack and Annie, perfect for readers who are just beginning chapter books
Merlin Missions: More challenging adventures for the experienced reader
Super Edition: A longer and more dangerous adventure
Fact Trackers: Nonfiction companions to your favorite Magic Tree House adventures