The submarine is an underwater vessel used by Marlo and her assistant Oslo in their endeavor to find and capture mermaids.
Story[]
The submarine was hidden underwater somewhere near a shore. It stayed down there for so long that it became unstable and needed a repair session. Unfortunately, since Marlo lacked the funds to get it fixed and the Mermaid Moon was fast approaching, she insists on skipping the tune-up and goes underwater with Oslo. They manage to capture Aquaryah and Chelsea, but the girls manage to escape with some help. The submarine ultimately can no longer handle the water pressure and breaks down, forcing Oslo to escape with an escape pod. Malibu manages to save Marlo by turning her into a mermaid, and they escape after Malibu awakens her power over water.
| Barbie: Mermaid Power |
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 Media: Barbie: Mermaid Power | Mermaid Power Soundtrack Characters: Aquaryah Aquavilla | Barbie "Malibu" Roberts | Barbie "Brooklyn" Roberts | Chelsea Roberts | Coralia | Dr. Tang | Isla | Finn Aquavilla | Marlo | Oslo | Puffy | Sareena Seasquid | Skipper Roberts | Stacie Roberts | Talleigha Fishtail | Viva Objects: Golden Pearl | Isla's Necklace | Submarine Terms: Power Keeper | Mermaid Moon Locations: Pacifica | Mermaid Rock Songs: "Make It Happen" | "Beneath the Surface" | "Turn It Up" | "Rise Above It" | "Find Your Power" |