Three teen girls are stranded on Mako Island, where a pool of water transforms them into mermaids in the series premiere of this animated version of "H2O: Just Add Water."
Emma enters a sand-castle competition. Meanwhile, Cleo looks after a challenging intern and rescues an injured sea turtle.
The girls find an old mermaid statue and intend to return it to an undersea wreck, but some treasure hunters may foil their plans.
A storm puts a birthday bash at a yacht basin in jeopardy, so the gals try to save the party and the birthday boy.
The girls try to halt the building of a luxury resort on Mako Island.
Emma is assaulted by some blue seaweed, which takes away her mermaid powers.
Lewis and the girls go to great lengths to stop the harm that discarded plastic bags are posing to the sea turtles.
An atmospheric disturbance leads to big trouble in Dolphin City and earns it the name "the new Bermuda Triangle."
Celebrities and a Hollywood production crew arrive in Dolphin City to shoot a movie, and trouble comes along as well.
Danny the octopus is snatched by an observation center, putting the upcoming volleyball tournament in jeopardy.
Lewis and the gals investigate some puzzling sound waves disturbing the whales, dolphins and mermaids.
A shark with a toothache seeks some relief onshore, but its presence could dampen Dolphin City's tourism season.
Rikki takes action after she spies on her dad and grows concerned about his relationship with his new girlfriend.
In the Season 2 opener, clown fish begin to vanish, so the girls investigate why this is happening.
Cleo forgets about her ability to change into a mermaid, so Emma and Rikki must make sure she doesn't transform in public
Lewis wants to share a big secret with Abby on Valentine's Day, and Cleo worries that he will tell her about the girls' mermaid identities.
Bobby's twin brother gets abducted by someone in a curious speedboat.
Cleo has some powerful nightmares after her father goes to sea on a mission.
Tired of the racket Miriam and Zane are making at their beach party, Bernie leaves his cave -- giving the Vandals a chance to move right in.
To protect the White Mermaid, the girls guide explorer Stanley Finch to the underwater stone circle, whose magic makes Stanley think he's a pirate.
When a spell forces Rikki to remain a mermaid until the next full moon, she has to find a way to lay low -- and underwater -- for three full days.
Lewis is thrilled when the university hosts an underwater robot competition, but the girls fret over the safety of their marine friends.
Emma's younger brother catches a glimpse of her mermaid tail and thinks he's seen a sea monster -- soon the whole town is in an uproar.
The mermaids turn to a cranky giant octopus for help when the Vandals invade the bay with a horde of stinging jellyfish.
Having played one too many practical jokes, Teddy can't get anyone to believe his warning that an underwater volcano is about to erupt.
Lewis joins a famous explorer in a high-tech submarine to hunt for a sunken treasure ship, but a mishap strands them at the bottom of the sea.
