Mako Island

Mako Island is an island that appears in H2O: Just add Water Mako Mermaids, and Trinity Of the Sea: The Series.

The location is a mysterious island in the form of a volcano. The island has The Moon Pool which allows whoever jumps in on a full moon to turn into a merperson, giving them powers, a tail, and the ability to transform 10 seconds after being in contact with water.