The open spaces in water's crystal structure make it possible for

The open spaces in water's crystal structure make it possible for aquatic life to exist at the north pole.

It is good to know that, at the north pole, when the temperature drops below zero, only the top layer of the water freezes. Underneath this freezing layer, water remains in its liquid form, thus, allowing marine life to exist. As for oxygen, it is also trapped underneath the ice layer.