In the mid eighteenth century, a mermaid named Eva used the Moon Pool in the Sea Caves of Ireland the create the original Tower of Light to change the course of a comet that was about to hit Earth. In the late 1990s, a young girl named Bella was transformed in the same place when she was nine years old. The first known people to become mermaids in Australia were Gracie, Louise Chatham and Julia, all of whom were transformed in the 1950s and were given special powers.
In Mid-2000s, Cleo Sertori, Emma Gilbert and Rikki Chadwick were transformed into mermaids in the Moon Pool. Charlotte Watsford, Gracie's granddaughter, also became a mermaid in the same place. However, as she entered alone and after the most recent planetary alignment, she received the three mermaid powers and its amplified versions.
The Moon Pool is destroyed in Season 3 by Sophie, Ryan and Zane.
Despite its destruction in Season 3, the Moon Pool somehow becomes active once again in Mako: Island of Secrets where a young boy named Zac Blakely regains his merman form and powers when he falls into the moon pool. Later, his girlfriend Evie McLaren would accidently become a mermaid as well. In Mako: Island of Secrets, the Moon Pool is completely different in appearance than how it appeared in H2O; the original entrance from land has disappeared, instead it was relocated to another side of the cave. According to Rikki in Mako: Island of Secrets, the Moon Pool's new appearance has been around since she and the others left, implying that they are somehow responsible for its remodeling. When the Comet was about to collide with Earth, the moon waterfall created a Water Tentacle to warn the mermaids about it.
As mentioned above, the Moon Pool has the power to turn normal people into merpeople when the Full Moon passes over. During this time, any human who jumps into the pool will be turned into a mermaid or merman, and given individual powers. The Full Moon generate different magnetism and effects depending on its phases and the planetary alignments.
Special Planetary Alignment
During a rare planetary alignment, the moon will increase the powers of a mermaid or merman, granting them amplified versions of their own powers if they are in the Moon Pool during the alignment.
The Moon of Fifty Years
At every fifty years another planetary alignment takes place. If a mermaid or merman is in the Moon Pool during this alignment, they will lose all of their mermaid powers, and will return to their original state as a Human.
During a Lunar Eclipse, any merperson who is in the Moon Pool will lose their powers for 12 hours. After that, the powers will return.
These effects apply only to human-turned-merpeople, because they became merpeople by the Moon Pool, and subsequently, the Full Moon reacts and can increase or remove their powers and mer-form according their alignments.
- There are two known Moon Pools in the world, one on Mako Island and other in the Sea Caves of Ireland. There may be more, but these two are the only ones known.
- Both the Crystals and Moon Rings store moonlight and can be used to simulate a Full Moon.
- These places were formed after a collision with a comet. The comet formed Mako Island, and other of its pieces formed the Sea Caves of Ireland and possibly more moon pools.
- A potion of full moon magic amplified by fifty which causes magic-made merpeople to lose their mer-form, has to be used in the Moon Pool during the Full Moon.
- It is revealed that if a human enters in contact with Moon Pool water, it gives them merperson powers that gradually loses balance.
- When a mermaid or merman is under the Moon Spell, the Moon Pool during a Full Moon will return them to normal.
- Main article: Moon Pool/Gallery