2. Memory Lapsse

When the stone circle causes Cleo to forget that she can turn into a mermaid, Emma and Rikki scramble to keep her from transforming in public.

3. Valentine's Day

Lewis promises to tell his Valentine's Day sweetheart, Abby, a big secret; Cleo is jealous and scared that he will give away the girls' mermaid identities.

4. Kidnapped!

The girls and Bobby the dolphin untangle a mystery when Bobby's twin, Robby, is captured by someone in a mysterious speedboat.

5. A Strange Phenomenon

When her father goes to sea on a mission, Cleo's worries begin to affect her dreams. Her nightmares could be trying to tell her something.

6. Handle with Care

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.

7. The Return of the White Mermaid

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.

8. Three Days Underwater

When a spell forces Rikki to remain a mermaid until the next full moon, she has to find a way to lie low, and underwater, for three full days.

9. Robot Duel

Lewis is thrilled when the university hosts an underwater robot competition, but the girls fret over the safety of their marine friends.

10. The Creature from the Bay

Emma's younger brother catches a glimpse of her mermaid tail and thinks he's seen a sea monster, and soon the whole town is in an uproar.

11. Underwater Takeover

The mermaids turn to a cranky giant octopus for help when the Vandals invade the bay with a horde of stinging jellyfish.

12. Imminent Danger

Having played one too many practical jokes, Teddy can't get anyone to believe his warning that an underwater volcano is about to erupt

13. Trapped

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.