User blog comment:Filheinz/Sudden realization/@comment-79.175.108.173-20121228154743

It is called for particular reasone the moonstone.

As you know the moon raises the water level, so if you crank up that force to the maximum it would be able to raize water to huge heights. And winter solstice is the moment when night is the longest, so she might wants to flood the world so Nami's people can return or something very important to happen.