The Moon Pool is a special, supernatural pool with the power to transform normal people into mermaids and mermen when a full moon passes directly over it's cone on top. The Moon Pool is located in a secret cave on Mako Island.There are currently two known moon pools: one on Mako Island in Australia and another in a Sea Caves of Ireland. These places were formed after a comet containing moon crystals that generated special powers corresponding to the moon crashed into Earth. The Moon Pool was destroyed in the series finale of H2O: Just Add Water, and it is somehow repaired in Mako Mermaids when Zac becomes a merman.
- The makers of H2O: Just Add Water and Mako Mermaids: An H2O Adventure made the Moon Pool. It is completely artificial.
- Until Mako Mermaids: An H2O Adventure is released, the only people affected by the Moon Pool's magic have all been female.
- The Mako Mermaids: An H2O Adventure moon pool looks completely different from the one in H2O: Just Add Water. It's the same place where Cam got out of control with the way that Zac grabbed a hold of the trident until it broke when he tried to rule the reef as a merman.