Mako Island was formed by a comet that crashed into the Earth. One of the shards impacted near Ireland (Eire) forming the Sea Caves of Ireland. Other shards would have landed in other locations creating moon pools wherever they impacted.
Mako Island has been around long before humans walked the earth and it will still be around long after humans have gone. Around Mako there are the largest population of Mako sharks and sea turtles, some of which cannot be found anywhere else on earth.There is also a secondary cave leading to a waterfall outside. The waterfall is part of a stream running through a mangrove forest.
Mako Island has a magical sea cave at its base leading to the Moon Pool, where Emma Gilbert, Cleo Sertori, and Rikki_Chadwick from H2O: Just Add Water became mermaids and Zac became a merman. It is possible that these other moon pools could have also created mermaids all over the Earth in other places and other times.
Off-shore there are coral reef sands and a number of wrecks. On the northern side of the island there is a place called Triton's Reef, its a known as place where sharks breed. Throughout history, there have been peculiar happenings aroung Mako, such as whirlpools and numerous ship wrecks and dissapearances, giving Mako an eerie reputation.