Book Series · 7 Books

Explorer Academy Books

In order from The Nebula Secret to The Forbidden Island.

Young explorers use science, technology, teamwork, and codes while pursuing a dangerous global mystery.

Reviewed by the Bookroo Editors Updated August 11, 2026

Reading order

How to Read Explorer Academy

Read Cruz's seven books from The Nebula Secret through The Forbidden Island in order. Then read the two-book Vela companion continuation starring Sailor York.

Sources: National Geographic's seven-book introduction, Disney's final-book page, Disney's Vela introduction.

For parents

What Parents Should Know

Expect a parent's death, sabotage, attacks, near-drowning, kidnapping, dangerous environments, criminal agents, a missing sister, and wildlife trafficking. Suspense is non-graphic and balanced by conservation, real science, and teamwork.

Where to start

Where Should My Child Start?

New to the school

Begin with The Nebula Secret.

Finished Cruz's story

Continue with The Sailor Cipher.

Where the story begins

First Book in the Series

Sale price

$958

Book #1 · Chapter Book · Ages 9–12 · 2018

The Nebula Secret

By Trudi Trueit, Scott Plumbe (Illustrator)

A young explorer uncovers a family secret that threatens his future at an elite academy.

216 pages· 52,975 words· Est. 6 hour read

5.8/7 Bookroo

$9.99Save 4%

Paperback

Summary: Twelve-year-old Cruz Coronado leaves Hawaii for the prestigious Explorer Academy, joining kids from around the world to train as future explorers. But Cruz's journey takes a perilous turn when he discovers his family's mysterious ties to the academy, putting his future at risk. Amidst thrilling classes and augmented-reality adventures, Cruz must unravel the enigma of who is targeting him and why. With puzzles and codes to solve, Cruz's quest for answers becomes a race against time. Can he uncover the truth before it's too late?

In reading order

Chapter Book · Ages 8–12 · 2021

Cruz faces a deadly foe and a life-altering secret on a perilous mission.

#6 in Series

Sale price

$958

The Dragon's Blood

Chapter Book · Ages 8–12 · 2021

A secret threatens Cruz's quest for the cipher's final piece in a life-or-death race.

#7 in Series

Sale price

$958

The Forbidden Island

Chapter Book · Ages 8–12 · 2022

Cruz races against time to unlock a life-altering secret amidst global dangers.

Two-book companion continuation

Explorer Academy Vela Series

1 book · Published 2024

Sailor York leads a connected mystery after the original series.

#1 in Series

Sale price

$1049

The Sailor Cipher

Chapter Book · Ages 8–12 · 2024

A sister's disappearance leads to a dangerous animal-smuggling mystery.

Good to know

Common Questions

How many books are in the Explorer Academy series?

There are 7 books in the Explorer Academy series. It began with The Nebula Secret in 2018, and the newest book, The Forbidden Island, was published in 2022.