Is it seen as wrong or inadvisable for a novel to have possibly two major climaxes in it? The problem I have is, my current novel has two story-lines running through it and at the moment it's looking as though one will be pretty much concluded two thirds in and the other towards the end. I could try and split it, but that would leave one story line loose and as it would be my first novel I sent to an agent, I know that wouldn't be a good thing. So yeah, basically, is it alright to have two climaxes in a novel?
There are numerous books out there with multiple climaxes. The first things that comes to my mind is: The Wheel of Time and A Song of Ice and Fire.
if you look at your story, it should consist of ups and downs. variation in pace, suspense, etc. most segments of a story have a build up and climax within themselves, so you probably have more than one already. as mentioned before - it all depends on how you handle it. - some authors would wrap up the smaller storyline first, and then go for the big blast, others have the big one, and then in a way of tidying up loose ends mention what happened to the other... i'd just try to maintain a difference in intensity between the more and less important storyline. Oh, and I seriously hate loose ends, unless it's a tv show (to be continued)...
I don't think this has to be a set in stone rule. I think a smaller aftermath climax can be quite effective. A good example would be The Lord of the Rings, after the main climax of defeating Sauron the hobbits return to their Shire only to find it under the tyranny of Saruman and have a final confrontation with him.
A novel pretty much needs more than one climax. It would be quite a spectacular feat to manage a steady build up to a single climax for anything longer than a short story. Even two climaxes would be low for a full-length novel.