The seaweed blanket

"When Maren and her younger sister visit lonely Aunt Pearl, they long to play in the sea but their aunt keeps them too busy until the dog accidentally gets out and a chase ensues. The girls are splashed by magical waves that turn their skin to scales, and they swim -- until they begin to worry about their aunt, left back home. They take her a blanket of wet seaweed which has the same magical effects -- leading to a glorious family romp. This is a...