The Quest of the Sunfish series by Mardi McConnochie

The Castle in the Sea book 2. ISBN 9781760290924
The Skeleton Coast book 3. ISBN 9781760290931
(Age: 9-13) Highly recommended. Themes: Adventure, Climate Change, Dystopian World, Friendship, Sailing.
Mardi McConnochie's futuristic The Quest of the Sunfish trilogy is set after the earth has experienced catastrophic flooding from a failed scientific experiment. While the Admiralty enforce strict rules and regulations, pirates roam the seas looting ships and boats. Environmental and social issues including climate change, poverty, slavery, bullying and the exploitation of technology and power underpin this fast-paced action adventure perfect for the preteen reading audience.
The Castle in the Sea begins several weeks after twins Will and Annalie, and their friends Essie and Pod escape from Lang Lang Island. Here, Annalie decoded the names and locations of four important scientists who worked with the twin's father Spinner on the secret Collodius Project. This novel focuses on their intrepid quest to trace and talk to each one, hoping they can find Spinner. From the start, they face one of the fiercest storms with high seas, huge waves, a broken mast and Will and Essie swept overboard. Annalie and Pod desperately attempt to mend the sailboat and fruitlessly search for their friends. Meanwhile, Will and Essie are cast ashore on a deserted island with an abandoned temple. Facing devious pirates, outwitting the Admiralty, sailing a raft across the dangerous sea, helped by talking dolphins, this fast-paced action adventure is a page-turner. With freedom from parental guidance, they learn to rely on each other, their individual strengths help them as they face each difficult situation. Resourcefulness, reliance on each other and trust are key to their survival.
The Skeleton Coast continues to deliver heightened drama. Pod's sister is rescued from slavery aboard a cruise ship and they face the desolate emptiness of the Outer Ocean.
McConnochie settings are richly detailed, challenging desert lands, deadly whirlpools and dangerous waters. Her detailed technology, modes of transportation, fierce and friendly her attention to the details of survival, the elemental fight between good and evil, all combine to make this series an exhilarating read. A detailed map of this kingdom would make an ideal addition, so we can follow their journey.
Rhyllis Bignell