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Underwater Investigation Unit Books in Order
Below you'll find the complete list of Underwater Investigation Unit books in publication order. This is generally the recommended reading order for the series.
Reading order verified: April 2026
Quick Answer
What order should I read the Underwater Investigation Unit series? Start with "The Girl Beneath the Sea" (2020) and follow publication order through all 5 books.
The complete Underwater Investigation Unit reading order is listed below in publication sequence.
Publication Order
The Girl Beneath the Sea
2020
Black Coral
2021
Sea Storm
2022
Sea Castle
2023
Dark Dive
2024
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