The Mysterious Bookshop

Osborne, Mary Pope, #9 Dolphins at Daybreak

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?