So, when did all the action happen?
The climax is like the bulk of the story, or when all the action comes in.
The climax is when Jason, Piper and Leo have to fight Porphyrion (the giant who was destined to destroy Zeus, therefore destroying Jason) and Khione while trying to save Thalia (Jason's long lost sister) and her Hunter friends, free Hera from an enchanted cage, and use their powers to destroy Gaea (earth goddess and villain, creator of the giants). The battle was what all their work on the quest added up to.
The climax is when Jason, Piper and Leo have to fight Porphyrion (the giant who was destined to destroy Zeus, therefore destroying Jason) and Khione while trying to save Thalia (Jason's long lost sister) and her Hunter friends, free Hera from an enchanted cage, and use their powers to destroy Gaea (earth goddess and villain, creator of the giants). The battle was what all their work on the quest added up to.