The Sea of Hoolemere is a large body of water surrounding the Island of Hoole upon which the Great Ga'Hoole Tree grows. Thick masses of fog often form above the sea that make navigation difficult. This fog also helps to conceal the true location of the Great Tree. This suggests they may be magical in origin. It is possible that the Ga' the Great Tree is imbued with exerts a magical influence on the weather that causes the fog to develop. The Pure Ones, and much later, the Striga and his forces, were able to bypass this protection and attack the Great Tree.