There are 5 books in the Underwater Investigation Unit series. The newest book is Dark Dive which came out in 2024.

1
The Girl Beneath the Sea

Book cover of The Girl Beneath the Sea

An Amazon Charts bestseller.

For a Florida police diver, danger rises to the surface in an adventurous thriller by the Wall Street Journal bestselling author of The Naturalist.

Coming from scandalous Florida treasure hunters and drug smugglers, Sloan McPherson is forging her own path, for herself and for her daughter,…

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2
Black Coral

Book cover of Black Coral
A Wall Street Journal bestseller.

For a police diver in Florida, solving a cold-case mystery brings a serial killer out of hiding in a deep, dark thriller by the Wall Street Journal bestselling author of The Naturalist.

Sloan McPherson and the Underwater Investigation Unit have discovered a van at the…

3
Sea Storm

Book cover of Sea Storm
A Wall Street Journal bestselling series.

An explosive conspiracy sets the ocean roiling for a deep-diving investigator in a riveting thriller by the author of the Amazon Charts bestseller The Girl Beneath the Sea.

A distress call draws rescuers Sloan McPherson and the Underwater Investigation Unit to a cruise ship…

4
Sea Castle

Book cover of Sea Castle
A Wall Street Journal bestselling series. A deep diving investigator is pulled into the depths of a string of unsolved serial murders in a riveting thriller by the Amazon Charts bestselling author of Sea Storm.

When a young woman washes ashore on a Fort Lauderdale beach, Sloan McPherson of the…

5
Dark Dive

Book cover of Dark Dive

A Wall Street Journal bestselling series.

Searching for a missing diver takes a Florida detective on a deep-diving adventure in a gripping thriller by the Amazon Charts bestselling author of Sea Castle.

After the Underwater Investigation Unit's disbandment, public outcry ushers Sloan McPherson and her partner, former navy diver Scott…