Emily Windsnap and the Crystal Caves

Emily Windsnap

by Liz Kessler, Erin Farley (illustrator)

Join the entire gang of mer-friends—and celebrate twenty years of Emily Windsnap—in this epic and masterfully crafted adventure by New York Times best-selling author Liz Kessler.

Adventure always seems to find Emily Windsnap! So when she discovers a bangle with a unique crystal under Rainbow Rocks, she and her friends are soon unraveling a whole new mystery. After learning that the crystal originally came from a familiar place—Halflight Castle!—Shona and Emily reunite there with Aaron . . . and none other than Neptune, king of the oceans. The bangle leads the mermaids to a cave full of crystals, and, with Mandy's help, they discover the truth about the jewel’s origin—and what’s at stake if they don’t make things right. Unfortunately, the only solution involves getting the sea and sky’s most powerful (and notoriously selfish) rulers to put their own interests aside for the greater good. Will the quartet find a way to convince the imperious Neptune and the Viking god Thor to come together to prevent disaster?

Genres: Fantasy

240 pages, Hardcover

Published May 6, 2025

About the author

Liz Kessler is the author of three novels about Philippa Fisher as well as the NEW YORK TIMES best-selling Emily Windsnap series. She lives in Manchester, England.

Reviews

[Ashlee · Rating 4 out of 5]

I’ve been a huge fan of the Emily Windsnap books since I was a kid! I was so excited when I saw a new book was coming out and even though I’m an adult now I couldn’t wait to read it. Well the book did not disappoint. I enjoyed every second I was reading it and could not put it down! I finished it within 24 hours and was sad to be done so soon. I really liked the educational component of this book like fault lines and tectonic plates. I remember being in high school and learning about those things so it was nice to see Emily connecting them to her real life. I love seeing her grow into her own person as each book progresses and I can’t wait to see what she does next!

[Victoria · Rating 4 out of 5]

Such a throw back and very, very cute and summery!

[Mark Buxton · Rating 4 out of 5]

What worked:
Humans and merfolk live together, and Emily is the daughter of a merman father and a human mother. The author resolves the logistics of living together by making their home on a boat. Emily has a human best friend named Mandy, and they attend high school together. Her mermaid best friend is Shona, and they attend Shiprock School with other merkids. She has remained friends with Aaron, an ex-boyfriend, and he joins Emily and Shona on their adventure to the ocean floor. The story is told in Emily’s first-person point of view.
Early on, the plot moves at a quick pace, which will appeal to young readers. Emily finds the bangle in chapter one and is already traveling to Halflight Castle by chapter three. The kids discover several improbable characters later, and the story slows down. However, these characters provide valuable information about past events, adding urgency and suspense. The plot’s tempo picks up again as Emily and her friends try to stop an impending disaster that can only be resolved through the cooperation of Neptune and Thor. How do they change the minds of two greedy gods?
The author may be sharing an opinion about environmental issues caused by humans. The crystal on Emily’s bangle comes from lava after a volcanic eruption in the ocean. Neptune orders his merfolk to mine the crystals as fast as they can, but his greed gets out of control. He always wants more wealth and extravagance, which also applies to the Norse god Thor. The prologue describes the war waged between these two gods and the far-reaching effects of their insatiable need to possess more. The crystals have a way to rebel against the abuse, but there may be a way to appease the Earth. The crystals seem to have a mind or spirit that reacts to the actions of humans and the gods.
What didn’t work as well:
The problem with a quick-moving plot is that it doesn’t go into great detail or description. Characters aren’t fully developed, although readers can learn more about them by reading the whole series.
The final verdict:
This book is the tenth in the series, but readers can still enjoy it independently. They’ll like the teamwork shown by the four friends, which is necessary to force cooperation on two greedy, stubborn gods. I recommend you give this book and the series a shot.

[Susan · Rating 3 out of 5]

In what Liz Kessler calls one last Emily Windsnap adventure teenage Emily enlists her friends from the human and mer worlds to get rival deities Neptune and Thor to rekindle their former friendship to save the planet from disaster.

The popular children’s series begins with preteen Emily Windsnap discovering when she jumps into the pool for swimming lessons that her legs fuse into a mermaid tail and reform as human legs when she gets out. In subsequent adventures, while tackling planetary threats like krakens and pirates, Emily discovers a family secret, that her father is full mer and was imprisoned by Nepture for marrying Emily’s mother, a human, gets her father released from prison to become Neptune’s trusted advisor, convinces humans and mer to put aside their longstanding mistrust and work together, learns to balance the social challenges of being half-human and half-mer, and navigates the emotional impacts of having a boyfriend.

Though not as creative as some of the other books in the series, in Emily Windsnap and the Crystal Caves, teenage Emily learns that she has a voice, stands up to adults for what is right, and faces her fears with poise and strength.

Note: After the success of the Emily Windsnap series recently Liz Kessler has turned her attention to other genres. When the World Was Ours is a provocative story of three children whose lives and friendship is changed as a result of the holocaust during World War II. Entirely different from Emily Windsnap, When the World Was Ours shows the breadth of the author’s writing ability and I highly recommend it.

[Johanna Koutikov · Rating 4 out of 5]

I love that everybody's character grew so much throughout the series; Beeston finally grew a backbone, Emily truly read Neptune to filth, and she's more likable overall as a person. The vast majority of the book was pretty epic, but I wish at the very end we could have seen how the adults process these insane events Beeston, the Windsnap parents etc. That part felt too abrupt for me. Like, your kid overthrows a god-king, but you don't discuss the aftermath, bruh.
P.S. The cover is stunning!

[Julie · Rating 4 out of 5]

The last Emily Windsnap book! It took us all year, but we did it! We read the whole series. My sister is pretty disappointed we don't have any more to read. Now we have to find something new to pick up. This book was a lot of fun to read. We had a good time with it and had a good time with the series as a whole. Kind of amazing that the year we decided to read the series together was the year she came out with one last book. It was fate <3 lol.

[Corinna · Rating 3 out of 5]

A fun addition to this series - it’s a classic Emily Windsnap-type plot, but because it follow that pattern it feels like a rehash of previous plots in a new skin
(also not me hoping Archie will make an appearance even after eleven years of NOTHING)

[holden caulfield · Rating 3 out of 5]

a good end to the series

[Caydence · Rating 4 out of 5]

Another great adventure that Emily embarks on! This one is fast paced and full of suprises. The ending is great too.

[Tatum Anderson · Rating 5 out of 5]

I can't wait for book 11!! I hope it comes out soon