The BEST Episodes of H2O: Just Add Water
Every episode ever - ranked by fan votes!
Last Updated: Dec 31, 2021
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!
#1 - Unfathomable
Season 2 - Episode 26 - Aired Mar 21, 2008
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?
9.01 
#2 - Three's Company
Season 2 - Episode 24 - Aired Mar 7, 2008
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.
8.99 
#3 - Bubble, Bubble, Toil and Trouble
Season 2 - Episode 22 - Aired Feb 22, 2008
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.
8.90 
#4 - Queen for a Day
Season 3 - Episode 20 - Aired Apr 13, 2010
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.
8.88 
#5 - A Date With Destiny
Season 3 - Episode 25 - Aired Apr 16, 2010
Cleo discovers a comet is causing fish to flee the waters around Mako Island. The girls find a way to restart the message in the Moon Pool and discover the comet will collide with earth. Sophie meets Ryan and with Zane's help they join forces to remove the crystals from the Moon Pool.
8.83 
#6 - Crime & Punishment
Season 3 - Episode 12 - Aired Jan 19, 2010
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.
8.79 
#7 - Kidnapped
Season 3 - Episode 8 - Aired Nov 4, 2009
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.
8.74 
#8 - The Heat is On
Season 2 - Episode 18 - Aired Jan 25, 2008
For the first anniversary of the girls being mermaids, Cleo decides to throw a party. However, Emma and Rikki fall out following a fight between Ash and Zane and Cleo may have to celebrate alone.
8.67 
#9 - Revealed
Season 3 - Episode 10 - Aired Nov 6, 2009
After Bella gives Will a shell-like fossil she found while swimming, Will becomes suspicious as the fossil is of a rare kind. Rikki realises how close Will is to finding out their mermaid secret and warns Bella to stay away from Will.
8.65 
#10 - A Twist in the Tail
Season 1 - Episode 26 - Aired Dec 29, 2006
Dr. Denman sets up a trap for the girls at Mako Island and Zane is forced to decide who he should be helping.
8.60 
#11 - Sea Change
Season 2 - Episode 25 - Aired Mar 14, 2008
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?
8.47 
#12 - Moonstruck
Season 2 - Episode 17 - Aired Jan 18, 2008
It's full moon and the girls insist that they don't need Lewis to assit his help as all three girls are staying at Emma's and Ash is coming over. When Cleo and Rikki fall under the moon spell, can Lewis stop them from revealing their secret to Ash?
8.44 
#13 - Stormy Weather
Season 2 - Episode 1 - Aired Sep 28, 2007
With Cleo's parents now divorced, Cleo is ordered by her dad to take more care of Kim, starting with taking her to a concert. But on the night, Cleo, Rikki and Emma all accidentally see the full moon, and take off to Mako Island, with Lewis in hot pursuit. Once there, the girls undergo another magical transformation in the Moon Pool, as a rare planetary alignment intensifies the power of the full moon – Emma's power is enhanced so that she can produce snow and frost, Rikki can conjure lightning, and Cleo can now control wind as well as water. After the moonstruck girls nearly harm Lewis, they realise that they must work to control their new powers, before anyone else gets hurt.
8.36 
#14 - Breakaway
Season 3 - Episode 19 - Aired Apr 13, 2010
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.
8.33 
#15 - Into the Light
Season 3 - Episode 18 - Aired Apr 12, 2010
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.
8.32 
#16 - Dr. Danger
Season 1 - Episode 25 - Aired Dec 22, 2006
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.
8.32 
#17 - Irresistable
Season 2 - Episode 15 - Aired Jan 4, 2008
Zane learns of the myth of Ambergris, a fragrance that can make mermaids fall for any man that wears it. When he buys it, Nate ends up wearing it and Emma, Cleo and Rikki all fall for him!
8.30 
#18 - Secrets & Lies
Season 3 - Episode 6 - Aired Nov 2, 2009
Bella tries to get close to Will but when Bella goes to his place she sees him with another girl. Meanwhile Lewis tries to test the water from the moon pool but gets caught by his teacher.
8.30 
#19 - In Over Our Heads
Season 2 - Episode 11 - Aired Dec 7, 2007
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!
8.24 
#20 - Wrong Side of the Tracks
Season 2 - Episode 8 - Aired Nov 16, 2007
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.
8.20 
#21 - Love Potion #9
Season 1 - Episode 24 - Aired Dec 15, 2006
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.
8.08 
#22 - Just a Girl at Heart
Season 3 - Episode 11 - Aired Jan 18, 2010
Bella helps Will with his free-diving training but when she realises he's more interested in her as a mermaid than a girl, she's hurt. Rikki and Cleo have to improvise when the cafe's first corporate function is actually a children‟s party.
8.07 
#23 - Too Close for Comfort
Season 3 - Episode 24 - Aired Apr 15, 2010
Don gets a second job at the Marine Park on the Pirate ship and outshines Cleo, threatening the future of her Dolphin show. Bella and Will find difficulty trying to connect with each others' interests.
8.04 
#24 - In Hot Water
Season 2 - Episode 7 - Aired Nov 9, 2007
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
8.04 
#25 - Fish Out Of Water
Season 1 - Episode 22 - Aired Dec 1, 2006
Emma and Cleo are concerned about Rikki going out with Zane. They force Rikki to decide to either be with Zane or with them.
8.02