The BEST Episodes of H2O: Just Add Water

Every episode ever - ranked by fan votes!

Last Updated: Sep 6, 2019

Network: Network Ten

Season One: The lifes of three girls living on the Australian Gold Coast are changed forever. When Cleo, Emma and Rikki stumble upon a pool inside the dreaded Mako Island, a full moon transforms them and the next day they start turning into super powered mermaids! With the help of friend Lewis, the girls manage to control their powers and hide their secrets. But it becomes difficult with maddening full moons, nosey scientists and local bad boy Zane going on a quest to find them! Season Two: Following the incident with Dr Denman and the Lunar Eclipse, Emma, Cleo and Rikki want to go back to their normal lives. But when the full moon comes back, all three girls have a dramatic power change! Without Lewis, they could destroy themselves. But their friend is trying his best to help them, despite his relationship with geeky Charlotte. But Charlotte proves to be more of a threat when she learns about her grandmother being a mermaid and stumbles into the moon pool and becomes a mermaid herself!

A Twist in the Tail

#1 - A Twist in the Tail

Season 1 - Episode 26

Dr. Denman sets up a trap for the girls at Mako Island and Zane is forced to decide who he should be helping.

star 8.65
48 votes
Directors: Jeffrey Walker
Writers: Philip Dalkin
Three's Company

#2 - Three's Company

Season 2 - Episode 24

More friction arises, this time over Lewis' birthday party. Charlotte takes control and drives Rikki away from the party. However, things go out of hand and it is up to her to save the day.

star 8.59
32 votes

#3 - Unfathomable

Season 2 - Episode 26

A unusual and rare planetary alingment is set to cause the full moon to remove a mermaids powers if they enter the moon pool! Charlotte shows immunity and tries to reveal the girls' secret before Lewis takes her to Mako Island. The girls follow and a battle erupts. But who will win?

star 8.56
39 votes
Treasure Hunt

#4 - Treasure Hunt

Season 2 - Episode 11

In need of cash, Rikki decides to go and searching for a lost statue with a huge reward. But she lies to Emma and Cleo, which causes danger when Rikki is knocked out!

star 8.47
38 votes
And Then There Were Four

#5 - And Then There Were Four

Season 2 - Episode 21

Charlotte's stubborn nature and thirst for knowledge leads her to Max, who confirms her suspicions and leads her to the Moon Pool. Lewis meanwhile is having trouble trying to keep their relationship together.

star 8.42
36 votes
The Gracie Code (2)

#6 - The Gracie Code (2)

Season 2 - Episode 20

Charlotte demands answers to why Lewis is hanging out with the girls so much. She starts to believe an excuse from Cleo, but then a discovery from inside Max's research brings her to the secret! Meanwhile, Ash decides to help Emma with her "fear of water."

star 8.39
33 votes
Bubble, Bubble, Toil and Trouble

#7 - Bubble, Bubble, Toil and Trouble

Season 2 - Episode 22

The girls decide that they should accept Charlotte, and the four work together when they need to join the volleyball team to avoid failing Physical Education.

star 8.25
28 votes
Riding for a Fall

#8 - Riding for a Fall

Season 2 - Episode 9

Emma has to take Eliot for horse riding lessons and the competitive perfectionist tries to be better than the instructor. Meanwhile, Lewis double dates with Charlotte and Cleo.

star 8.24
41 votes
Writers: Susan MacGillicuddy
Wrong Side of the Tracks

#9 - Wrong Side of the Tracks

Season 2 - Episode 8

Zane is curious by Rikki's reluctancy to reveal where she lives. So one day, he eventually convinces her to reveal her home: a trailer park with her grouchy father.

star 8.24
41 votes
Writers: Sam Carroll
In Hot Water

#10 - In Hot Water

Season 2 - Episode 7

Everyone is shocked when Cleo is fired at the Ice Cream Stand, and even more so when Lewis takes her place! Rikki and Emma strike back at him but end up going too far

star 8.24
38 votes
Writers: Joss King
Into the Light

#11 - Into the Light

Season 3 - Episode 18

Rikki fears Ryan's explorations on Mako Island will uncover their secrets but Cleo and Bella discount her concern. She almost goes too far trying to stop Ryan from discovering the crystals in the Moon Pool.

star 8.21
29 votes
Directors: Colin Budds
Writers: Sam Carroll

#12 - Graduation

Season 3 - Episode 26

Sophie and Ryan damage the Moon Pool in their efforts to obtain the rare crystals. The girls improvise and use their own magic to prevent the impact of the comet and a planet wide catastrophe. Rikki, Cleo and Bella graduate with a surprise.

star 8.20
45 votes
Directors: Colin Budds
Writers: Joss King
The Denman Affair

#13 - The Denman Affair

Season 1 - Episode 8

Lewis is offered a great job with a marine biologist, but the girls are concerned that his interest will cause him to reveal too much information

star 8.16
51 votes
Directors: Colin Budds
Writers: Chris Annastassiades
Queen for a Day

#14 - Queen for a Day

Season 3 - Episode 20

Zane installs Sophie as head of staff at the cafe. Bella develops a sneezing allergy that also accidentally triggers her powers. Sophie seizes on the problem and looks to fire Bella and the band.

star 8.15
34 votes
Directors: Colin Budds
Writers: Samantha Strauss

#15 - Kidnapped

Season 3 - Episode 8

During a full moon, the girls stay at Cleo's and Bella is attacked by the water creature. At the same time, Will decides to return to the moon pool after making the connection between his previous encounter with the moon pool waterfall and the timing of the full moon.

star 8.15
41 votes
Directors: Jeffrey Walker
Writers: Chris Roache
Sea Change

#16 - Sea Change

Season 2 - Episode 25

Angry over the short friendship with the girls, Charlotte forces Lewis to choose between her and his friends. This results in Cleo to feel isolated and she runs away and gets lost. When he is informed, Lewis must make up his mind: Cleo or Charlotte?

star 8.14
28 votes
Dr. Danger

#17 - Dr. Danger

Season 1 - Episode 25

It's time for Emma's family's annual vacation trip, but she can't go as the risks are too high. But all her excuses don't go very well with her family. Meanwhile, with the return of Dr. Denman, Zane is closer than ever to cracking the girl's secret.

star 8.13
45 votes
Directors: Jeffrey Walker
Writers: Sam Carroll
Pool Party

#18 - Pool Party

Season 1 - Episode 2

Annoying Miss Popularity, Miriam, is having a pool party and the girls want to go. But being around water is risky, especially when Zane tosses Cleo into the pool. Lewis is the only one around to help so he finds out their secret.

star 8.12
121 votes
Directors: Colin Budds
Writers: Deb Cox

#19 - Breakaway

Season 3 - Episode 19

Will competes in the Free-Diving Championships but afterward chooses to break from the sport and shrug off Sophie's influence on his life. Rikki sees Sophie kissing Zane at the event and breaks off their relationship.

star 8.12
33 votes
Directors: Colin Budds
Writers: Anthony Morris
Crime & Punishment

#20 - Crime & Punishment

Season 3 - Episode 12

Rikki receives counterfeit money at the cafe and is held captive by criminals on a boat. Bella and Cleo are forced to reveal the trio's secret to Will so they can rescue Rikki together.

star 8.11
35 votes
Directors: Jeffrey Walker
Writers: Max Dann
Under the Weather

#21 - Under the Weather

Season 1 - Episode 17

The girls have to fake sick as a result of a thunderstorm, so their secret won't be discovered at school. But their 'sickness' attracts the attention of doctors.

star 8.11
54 votes
Directors: Jeffrey Walker
Writers: Max Dann
Love Potion #9

#22 - Love Potion #9

Season 1 - Episode 24

With the school dance coming up, Emma and Cleo hope Byron and Lewis will ask them out. Meanwhile, Miss Chatham and Lewis are arguing about which is more important, magic and science.

star 8.10
42 votes
Directors: Jeffrey Walker
Writers: Anthony Morris
The Dark Side

#23 - The Dark Side

Season 3 - Episode 16

Rikki's frustrated by the water attacks and goes to Mako Island on a full moon to confront the strange force in the Moon Pool. With Cleo and Bella delayed, Will pursues her and discovers she's been affected by the experience.

star 8.09
35 votes
Directors: Colin Budds
Writers: Sam Carroll
The One That Got Away

#24 - The One That Got Away

Season 2 - Episode 3

Rikki tries to avoid Zane when he comes back, but needs his help after an incident with a speedboat. Meanwhile, Charlotte continues to flirt with Lewis and Cleo worries for their secret.

star 8.08
49 votes
Directors: Jeffrey Walker
Writers: Anthony Morris
The Sorcerer's Apprentice

#25 - The Sorcerer's Apprentice

Season 3 - Episode 9

Cleo starts to experiment on the moon pool water without Lewis' knowledge, but things start going wrong when Cleo's fish Hector gets trapped in the bubble of floating water. Meanwhile, Lewis has to play golf with Cleo's father.

star 8.07
40 votes
Directors: Jeffrey Walker
Writers: Philip Dalkin