Great Scarrier Reef (location)

The Great Barrier Reef is located in the Coral Sea, which itself is located off the northeast coast of Australia. It is the largest coral reef system in the world and home to various salt water monsters.

History
Lagoona Blue lives at 4004 Davy Jones Cir, which presumably is the address of her mother's cave. Though nowadays Lagoona mostly resides in the USA to she can attend Monster High, she usually uses her vacations to go home to the Great Barrier Reef.

On one particular visit to the Great Barrier Reef, Lagoona was sent a luxurious boat by her parents so she could bring along her friends. Lagoona was mostly stoked about the opportunity to introduce her boyfriend, Gillington "Gil" Webber, a fresh water monster, to her parents. Gil was everything but happy to go, but when the ship got sunk and Lagoona and their friends lured to and captured on Skull Shores, Gil swam the remaining distance to the Great Barrier Reef on his own to get Lagoona's parents to help. Gil found the Blues to be less terrifying than he imagined, and after saving Lagoona and their friends, the group presumably had an enjoyable Spring Break at the Great Barrier Reef.