07/22/2026
H2O: JUST ADD WATER – SEASON 4: DEEP BLUE LEGACY (2026)
Starring: Phoebe Tonkin • Cariba Heine • Angus McLaren • Indiana Evans
Genre: Fantasy • Adventure • Drama • Family
Tagline: "Some secrets belong to the ocean forever."
A decade after the extraordinary events that forever changed their lives, Cleo Sertori and Rikki Chadwick have learned to balance ordinary life with the extraordinary secret they have sworn to protect. Far from the carefree summers of their youth, the modern world has become increasingly connected, leaving fewer places where magic can remain hidden. As mysterious environmental disturbances begin spreading across Australia's coastline, ancient forces awaken beneath Mako Island, threatening to expose the existence of mermaids to the entire world. Drawn back together by an unexplained surge of oceanic power, Cleo and Rikki soon discover that the Moon Pool is changing in ways no generation has ever witnessed before. Joining them is Bella Hart, whose unique connection to water proves vital as an ancient relic surfaces from the depths, carrying the forgotten legacy of the first mermaids. Meanwhile, Lewis returns after years of marine research with alarming discoveries suggesting that powerful corporations are secretly searching for Mako's supernatural energy, willing to exploit its magic regardless of the consequences. As dangerous expeditions, breathtaking underwater adventures, and long-buried secrets collide, the three women must mentor a new generation destined to inherit the ocean's greatest responsibility before greed destroys the fragile balance between humanity and the sea. Filled with spectacular underwater cinematography, breathtaking coastal landscapes, heartfelt friendships, emotional storytelling, and the timeless sense of wonder that made the original series beloved around the world, H2O: Just Add Water – Season 4: Deep Blue Legacy celebrates courage, friendship, legacy, and the enduring belief that the ocean always protects those who respect its mysteries.