Head First

by Claire Kershaw

Two rival marine biologists, an extremely small boat... and one very big lie.

Andi has learned to love her predictable life in Ohio. But when her marine biologist sister needs emergency surgery, Andi agrees to take Millie's place on the trip of a scuba diving on the Great Barrier Reef. There's just one Andi must pretend to be Millie the entire time.

But when Andi arrives in Cairns, she is horrified to learn that Hugh Harris - Millie's professional rival and extremely vocal social media critic - is also on-board. And he's very handsome. Perfect.

Somewhere between the sunsets and the beauty of the underwater world, Andi begins to question the mundanity of her life at home and whether she is capable of being the woman Hugh believes her to be.

But how can you truly fall for someone when they think you are someone else?

Genres: Romance, Contemporary, Book Club

342 pages, Paperback

Published May 22, 2025

About the author

Claire Kershaw is the author of Head First, a Great Barrier Reef inspired romance. Apple of My Eye is her second novel. Since graduating from Emory University with a degree in English Literature, Claire has moved to the Pacific Northwest, where you can find her hiking, tending to her many houseplants, or scribbling half-baked plot ideas on scraps of paper.

@clairekershawauthor

Reviews

[Natalie M · Rating 2 out of 5]

Not my cup of tea at all.

I loved the premise and i was looking forward to the setting (diving the Great Barrier Reef) but everything felt flat and one dimensional. I was not invested in either sister or their reasons for decisions and choices. As this happened at the beginning of the novel, the feeling never left me.

Other readers have loved this book, so give it a go.

[Grace Fuscoe · Rating 5 out of 5]

Best book of 2024

[Whit Rapp · Rating 5 out of 5]

This author is destined for something great!

[Joanna Dixon · Rating 2 out of 5]

I found this book very frustrating for many reasons.. Why, in Rom Coms, do people start relationships entirely based on lies, but it's all fine because they're attractive??? Red flags, people. The female protagonist was likeable but quite irritating at points, and although doing things for the right reasons (predominantly) made a lot of questionable decisions.. Meanwhile the male protagonist was treated very poorly, lied to the entire time, and then immediately forgave her and said he trusted her heart was in the right place. Just felt very unrealistic. I did enjoy the setting of them diving in the Great Coral Reef though, even though this also had huge plot holes!

[Kasey Fuscoe · Rating 5 out of 5]

Absolutely loved this! What a fantastic, fun, engaging read.

[Mathilde Hoogland · Rating 4 out of 5]

honestly i wasn’t expecting to like it so much!! maybe even 4.25?? i loved the setting and the descriptions of the dives they were going on 🪸🐠 at first Hugh was kind of an asshole and the book and characters felt a little bit flat, but after some time that wasn’t the case anymore for me. there’s just one negative thing i want to point out: i think Hugh got mentioned every page about 6 times 😩 there was a lot of tension building between Andi and Hugh (which was done super well), but i hoped the book focused some more on Andi’s development througout the book. oh and one more thing: i really liked the side characters that were on the boat with them, they added a lot to the story.

[Elin Berggren · Rating 3 out of 5]

Hemma sjuk, då lyssnades denna ljudbok på - hela dagen. Hade inte ork för mycket annat än att bara blunda och lyssna.
Helt okej, den känns lite som en feberdröm nu i efterhand dock pga sagd sjukdom. Något platta karaktärer och hade kunnat önska mer av författandet av storyn, men ändå en helt okej rom-com bok!

[Millie Cole · Rating 5 out of 5]

LOVE! Could possibly be book of the Summer 🌺✨🐠

[Laura · Rating 2 out of 5]

meh

[Helmi · Rating 4 out of 5]

Loved the setting, it was a nice and easy read = perfect for summer!

[Fabiana Brown · Rating 5 out of 5]

Such well-done romantic banter. I want to go scuba diving!!

[Rozh · Rating 5 out of 5]

What a fun read, made me want to go to the great barrier reef immediately.

[Bente Bergsma · Rating 4 out of 5]

leuk onderwerp om over te lezen tussen de romance door! 🐠🐙🦈

[Saga Nord · Rating 2 out of 5]

Is not bad but nothing special

[Emily Bovill · Rating 3 out of 5]

two rival marine biologists are forced to work together on a research expedition, but as the truth surfaces, the question remains: can you fall in love with somebody you don’t know?

this story has a unique plot and setting. as someone who knows nothing about diving, this story was easy to follow along with, and i could easily picture this in my head. it was a fun getaway with a cute romance to root for.

[Julie Malone · Rating 5 out of 5]

This is not my typical genre, but Claire made this book so fun and lovely to read by creating a world that I want to be a part of! The scuba scenes are so visually evocative, and the dialogue is *actually* realistic. I loved the characters, their values, and their dynamics. Fun read!

[Margaret Karleskind · Rating 5 out of 5]

I NEED a movie adaption. This was the perfect modern romance read that also raised awareness for an important cause. The author did a wonderful job of balancing the story and a really powerful message. 10/10 I can’t wait to read more from the author. Well done! Do not miss the message from author at the end. Great read, I couldn’t put it down.

[Tabs · Rating 4 out of 5]

3.5🌟 𝘛𝘩𝘢𝘯𝘬 𝘺𝘰𝘶 𝘵𝘰 𝘉𝘰𝘯𝘯𝘪𝘦𝘳 𝘉𝘰𝘰𝘬𝘴 𝘜𝘒, 𝘡𝘢𝘧𝘧𝘳𝘦 𝘢𝘯𝘥 𝘕𝘦𝘵𝘎𝘢𝘭𝘭𝘦𝘺 𝘧𝘰𝘳 𝘱𝘳𝘰𝘷𝘪𝘥𝘪𝘯𝘨 𝘮𝘦 𝘸𝘪𝘵𝘩 𝘢𝘯 𝘦𝘈𝘙𝘊.

Andi is the safe, predictable sister with impeccable grammar (insult her work at your peril). Millie is the adventurous, outgoing sister with a degree in marine biology and an upcoming research trip of a lifetime to the Great Barrier Reef. When a medical emergency sees Millie unable to travel to Australia, she begs Andi to go in her place... the twist? In order for the research and findings to be valid, Andi must pretend to be Millie. Easy, right? Especially when you're stuck on a small boat with nowhere to escape to, your sister's hot marine biologist internet/social media rival (Hugh Harris) happens to be on the same trip, and you're pretty sure another charter guest overheard someone say your REAL name in the airport. What could possibly go wrong?

Or what could possibly go very very right...

This has got me SO READY for summer. It's suncream and salty skin and tangled hair and freckled noses and swaying hammocks. It's rivals to lovers, mistaken identity, forced proximity. Anyone who has ever spent a few days on a live-onboard boat knows what an incredible pocket dimension it can be - everyone is in your space, food is eaten communally, you struggle to walk straight as soon as you step foot on land, and you can jump off with a snorkel whenever you wish and uncover a hidden world beneath the waves. It's a pure kind of magic that Head First taps into so well. I also loved the scenes of them all scuba-diving. It's such a difficult activity to properly describe to those who have never done it before, but you can feel Andi's wonder and excitement leap straight off the page.

When it comes to the core romance, they're only on the boat for a few days, so there's no slow-burn here. It's as sizzling as the overhead sun (though I did appreciate that the FMC (under the guise of Millie) & MMC had messaged a bit before the trip so the relationship didn't feel too insta-lovey). What happens when an immovable force (Hugh's best practises and marine biology ethics) meets an unstoppable force (Andi will scrap anyone that prevents her from finding the fish her sister sent her there to locate). There's some delicious tension to be found in it all, even though it's completely ridiculous and farcical. Andi is panicking 24/7 while also trying to mitigate her growing feelings for the super-tanned, super-muscled, Australian fish man (Hugh). It's a little repetitive and mis-communication-y (she needs to tell him WHO SHE IS, but also she CANNOT POSSIBLY tell him WHO SHE IS), but still fun.

If I was going to have one main criticism, it's that I wanted more fish facts. What I find worked so well in Ali Hazelwood's STEM romances is that the characters are absolute NERDS and really respect one another's research/brains/enthusiasm. I get that Andi only knew so much (which is fair given she hadn't studied marine biology since college), but Hugh? I wanted to see that man fanboying over sea slime. I wanted to see him LOSE HIS SHIT over a specific coral formation and then regale the boat with highly specific and completely unnecessary anecdotes about said coral formation.

Absolutely one to look out for if you're in the mood for something sun-soaked and transportive. A solid core romance, a fun cast of side characters, a stunning backdrop, an examination of familial relationships (guilt, expectation, growth, jealousy), and what it is to work on yourself and rediscover what you want out of life.

Head First is publishing May 22nd.

[Lou · Rating 3 out of 5]

Thank you to Netgalley and Bonnier Books UK for providing an ARC of this book.
The story picks up pace quickly and we get introduced to our FMC Andi, who studied Marine Biology in college, works a corporate job, and just broke up with her long-term boyfriend. Now, she is unsure what to do with her life, everything seems dull to the point she’s asking herself whether to pick up knitting and I’d say: yes! Go for it, knitting is a great hobby. Some might even say, picking up knitting would have been a better idea than picking up a guy, but I’m getting ahead of myself.
We also meet her sister Millie, who is actively researching as a marine biologist and want to go on a trip to Australia over the holidays to find a fish her rivalling marine biologist believes to be extinct. However, she has to get an emergency surgery and Andi has to go in her stead.
This premise got me thinking “okay, but how is this actually going to work… like, logistically?”
Turns out, quite conveniently, Millie and Andi look alike (almost like twins) and Andi has kept up with Millie’s research (having studies marine biology herself for a bit and being her grammar proof reader on every paper). Since scientific papers are usually a team effort, there’s nothing wrong with having someone proofread your work. It would, however, also imply that other scientists are involved in the making of the paper, so why does Millie think it’s a better idea to send her majorly unqualified sister instead of someone from the lab she works at? We do not know, but Gen Z people say “do it for the plot” and I guess the author did just that.
And Andi did spend a couple days studying corals of the Great Barrier Reef… apparently all 600 of them.
What I liked about the book:
- the diving scenes
- the banter

What I didn’t like about the book:
- Every time Andi is flirting with Hugh, “sweat prickles in the back of [her] knees”… what?!
- rippling abs/muscles… why?
- the couples/side characters were confusing, I honestly couldn’t distinguish them until halfway through the book
- referencing another romance book (Beach Read, by Emily Henry) in the book as a novel the protagonist is reading (reminds me I should've rather read Beach Read instead)

This does in no way re-invent the wheel. It’s also not the most emotional or touching romance I’ve ever read. It is light-hearted, the perfect read for in-between or while on vacation if you want to read something for entertainment only without having to use your brain too much (which I do not mean as criticism, all contemporary rom-com books fall under this category for me).

[Andie · Rating 1 out of 5]

There are aspects of this premise that I normally like, particularly in a romance. Namely, I adore the P&P set-up where someone makes incorrect (or in this case, misplaced) assumptions about the protagonist's character.

Unfortunately, the book doesn't deliver the promised interpersonal intrigue and is riddled with suspect politics. To summarize the red flags:
- The MMC corrects the FMC's grammatical error, then makes a mistake of his own (the wrong "whose" vs "who's") which the FMC doesn't comment on, leading me to believe it was an authorial typo. I can overlook some proofreading errors, but it feels egregious when the characters are actively discussing grammar. Neither the author nor her characters should be casting stones.
- In an inane battle of "whose country is better", the American FMC accuses the Australian MMC of living in a country that was stolen from Indigenous people, which also goes unchallenged for hypocrisy. (And America is better ... how?)
- Most characters appear surprised to learn about "global warming" and its impact on coral, although the FMC is trying to prove that pollution is primarily at fault. This (on top of the grammatical errors, revisionist history, and use of "global warming" in lieu of "climate change") left me wondering if the author was educated in a red state.
- There is a nod to "right to choose", though this is promptly followed by "the ocean is not a place for politics". (While this is laughable in its own right, it's made doubly so when the FMC skips a panel on the International Tribunal for the Law of the Sea at the end of the book.)
- A few pages later, the MMC asks the FMC what she wanted to be when she grew up. His first two suggestions are: "A mom? A wife?"

I could explain why this book doesn't work, structurally, but the above issues were sufficient for me to one-star it and return it to the library.

[Paige| apaigeinthechapter · Rating 3 out of 5]

As soon as I heard this was a summery romance following rival marine biologists, I knew I would like this, and I did. Head First had me completely immersed in the summery vibes despite reading it in front of my Christmas tree, and I will now be spending too much time staring mournfully at the cost of plane tickets to Australia.

The pacing of this deserves some credit because it should feel long given how much content the plot covers, but I read it in one sitting and it felt like a light easy read. I also feel like the amount the plot covers is necessary for the relationship development, and had we not seen so much content from the boat/dives, it would be harder to root for the character's relationship (and root for them I did).

My only critique is that I didn't love that the characters progressed so far in their relationship under false pretences. I wish Hugh would have found out sooner as it made me feel a little icky, and I also would have liked to have experienced that conflict for a little longer and really explore it. Once the boat trip is over the story starts to feel a little bit rushed, and I would have liked to have seen the characters navigating the conflict around each other rather than being separated. However, I was impressed that I could root so hard for a couple whose relationship was built on a lie so I feel like is an excellent example of the mistaken identity/lying about identity trope.

I thought this was a really fun, light-hearted, and easy read, and I will be recommending this to people for their summer or beach holiday tbrs. Whilst this is marked as 3 stars, it was more of a 3.5 for me and was a totally solid romance.

[B · Rating 3 out of 5]

I think its hard enough for an author to write multiple fullly fledged characters as it is, but this book was also written in a singular 1st person pov, which did it no favours. Nobody else felt like a full person. The love interest (Hugh) especially, was very simple, and in a romance I really want to know everyone in the relationship, so I was disappointed.

I liked the idea they were going for, and while I understand it's fiction, many things just seem to have plot holes or be unrealistic, coming from a STEM background myself, these inconsistencies really grated at me.

The setting was described beautifully, and while I'm deeply afraid of the ocean, it managed to make me wistful for a vacation in a similar setting. Though I'm not sure how much I trust the charactersl's judgement of the people or the country considering she was in the "country" for 5 days, spent isolated on the ocean in a boat, full of mostly international people, with only a short taxi ride on either side of her trip...

It's a fun read if you know going into it the relationship is built on a lie and don't mind that, and are looking for a fun flirty read for the summer. Just don't expect it to hold much water.

Thank-you NetGalley and Bonnier Books UK, for giving me this opportunity to read the ARC. All opinions are my own.

[Lucca Powers Bates · Rating 4 out of 5]

Rating: 3.5 stars

Read if you like:
- Academic rivals to lovers
- Forced proximity
- Secret identity (she's posing as her sister)

I'm a sucker for an academic rivals to lovers book, and this one did it so well! It's the first one I've read with this marine biologist plot which I loved. The pages really flew by when reading. The romance between the two main characters is fun and good.

Secret identity plots aren't usually my favourite as I'm often left frustrated by why they didn't just come clean sooner. There was a bit of this here, but it's definitely not that bad because it's only over the span of a week.

The romance between the two main characters is fun, though I did slightly prefer the beginning where we still had the rivalry banter. The romance was also a bit *too* insta-love without me really feeling the depth of their connection. The FMC also frustrated me a bit towards the end with her overreaction to the MMC.

On the whole, a super fun summer read that I definitely recommend - great to just bring with you on the beach and you'd finish it in a day!

Thank you so much to the publisher for sending me a copy of this book!

[Audry Rimland · Rating 5 out of 5]

I loved this book! It was so beautifully written and well-paced. It's just a perfect summer read. It's got a healthy dose of inspiration to chase your dreams, stunning descriptions of the exotic location, and lovely side characters. I often struggle with books with a large cast of characters, but the people in Head First have such well-defined ways of speaking/clearly defined mannerisms, it made keeping track of the many (ok there's like 10ish but I get overwhelemed) characters easy. Claire is a great writer and storyteller!!

This is just such a good book to give as an Easter or Birthday gift for someone who's going on a diving or boat based Summer Holiday. I've never been diving, but this book made me somehow less intimidated by it, and also more aware of the seriousness of the activity. So if you're curious about diving, I feel like this is a great book for you too!!

Lots of likeable characters and really great banter. I think this is the 2026 summer beach read, I'm calling it!!

[Louise Searle · Rating 4 out of 5]

Head First follows Andi, her sister Millie (a marine biologist) wants to prove that a certain fish is not yet extinct and is planning on a diving trip to Australia to prove it. However when she receives some bad news Andi goes on this trip for her while also pretending to BE her. The only thing is… Millie’s online nemesis is also on the boat with her.

I LOVED the concept of this book, I love animal science and can’t help but be a bit biased toward women in STEM.

The banter between Andi and Hugh was top notch and I could feel the tension between them the whole way through the book. Even though I loved how Andi was willing to do anything for her sister I was still begging her to tell him who she was the whole time!

Claire did an amazing job describing the underwater reef scenes I could picture them beautifully in my head and she definitely did her research on marine biology!

Overall I really enjoyed reading this. It was funny, emotional, tense and inspirational!

[Fiona · Rating 3 out of 5]

I really enjoyed this book and the overall plot. There were such great happy moments, moments where the tension really gripped you into the book and encapsulates you.

The MMC was great although I do wish we got some more intimate moments with him, it feels as if I barely know him?

The ending did feel a little bit rushed and we never find out about what happened with the letter she sent. Like did some else interject it? Was it lost? Like why didn’t he receive her letter 😣 maybe it’s just me, but I want to know these details no matter how small they may seem.

Also, regarding the FMC’s sister we don’t hear about her health, which I understand she’s not a main character but her situation was what led to the whole plot of the story and we never truly get to find out about her health and if she’s better until the end I guess but even that is a long shot of a guess.

Overall, good story and a good read for summer.

[Poppy Cain · Rating 3 out of 5]

A Cute Academic-Rivals-to-Lovers with an identity twist.

I went into it expecting something similar to Ali Hazelwood's STEM romances as the premise is between two Marine Biologists stuck on one small boat in the ocean trying to prove each other wrong, but ended up getting disappointed by the lack of consistency with the reality of being Marine Biologists and the experience of working in the field.

The back and forth was cute, but I also felt there was a penchant for instant attraction that didn't help support the romance overall.

Perfect for anyone who wants to read some fluffy romance, less perfect for those who are actually experienced scuba divers or in STEM as inaccuracies and academic misconduct (swapping identities with your PhD twin to gather data for a scientific study would get you blacklisted from the industry) pop up here and there.

[Jess 😻 · Rating 4 out of 5]

4/4.5 🌟

Thank you to netgalley for an arc of this book!

This was such a great read! I loved the setting I loved the characters, and it flowed really well. Of course hearing about diving in the Great Barrier Reef is amazing and such a dream and I loved seeing how much it changed Andi and encouraged her to change her life to what she wanted. I loved the sisterly bond between them and how it only grew better once she returned.

The romance was also great and although Andi frustrated me with not telling Hugh, I did see her side of it and I’m glad that it worked out the way it did in the end - I think if they instantly got together I would’ve found it unbelievable.

Overall a great read if you’re looking for a bit of spice & summer vibes

[amys_books0 · Rating 4 out of 5]

I loved this book ! The chemistry between the two main characters was everything.

This book had a really good pace which made me finish it in one sitting. Head First had many laugh out loud moments which is rare to find in some books.
I loved the plot of this book and it the marine biologist element of the book was interesting to read. The tropes of this book as well were perfect. I love a rival to lovers trope and forced proximity trope which made me really enjoy this book.

Head First is such a light hearted, laugh out loud read and would be a perfect read for a sunny day. I loved the authors writing style and cant wait to read any more of their books.

*Thank you NetGalley and Bonnier Books Uk for providing me this arc in return for an honest review*

[Brittany Steminist Booknerd · Rating 3 out of 5]

STEM romance! This was a cute marine biologists rivals to lovers romance with a twist. There’s a purposeful mistaken identity that causes a bunch of issues. That part gets a bit repetitive and frustrating as you get closer to the end of the book. It feels a bit like self-sabotage. It’s a really slow burn with very light spice, but as we got to the big spicy scene, there was no discussion about protection or prevention or anything, just in and out which was a bit icky for me. If you liked Love Below Zero, you might like this one. There are some similar tropes in both books (online rivals to lovers, STEM romances, forced proximity for science, slow burn). It was well written, the plot was ok, and the spice was very light.