Physics in Fantasy Stories

So I am writing a fantasy novel and the problem that I've had lately is that I can't make a fantasy novel realistic. 

I know. That sounds really stupid.

But think about it: I'm writing a fantasy novel and I keep running into this problem where I can't make the physics work in the story.

Take this example: if I write a story that takes place underwater, then I have the problem that furniture floats, things like books can't exist, and if a person bleeds, where does the blood go? So many things just don't work and you don't think about it until you try to write it. 

Now an easy solution to this problem is when the story is somewhat juvenile or silly. Take the Little Mermaid. No one questions the fact that Ariel hoards paintings and books and they never get damaged. Of course, that story is also about a girl selling her voice to an evil sea witch in order to get legs to win a man.

Not exactly realistic.

Another perfect example is Spongebob Squarepants. No one thinks it's at all unusual when Spongebob lights a fire, or that there is an underwater ocean called the Goo Lagoon, or that he lives in a pineapple. No one questions this because it's just silly and it isn't supposed to be serious.

So what do you do when you try to write a serious young adult fantasy novel? You can't just ignore physics because it makes the story sound cheap and silly. This is the problem I've been wrestling with. I'm trying to write this serious, intense, somewhat dark fantasy novel, but I just can't ignore the physics anymore. I've been trying to figure out what to do. 

But then I realized something: What's the point of writing a fantasy novel if you can't bend the rules a little, so to speak? If I'm writing a story about a mermaid who is also a siren and is in a struggle for her life against her mother who wants to essentially change her race, then I am already suspending reality, so why not go all the way?

Go big or go home.

But seriously, why am I worried about perfectly following the rules of physics when I am already writing a story that defies the natural world?

So the conclusion I came to is that if one day this book is published and people choose to read it, they are already suspending reality to read a story about mermaid. It isn't too much to ask to expect them to suspend general rules of nature as well.

Of course, I'm not going to go as far as to light fires underwater or live in a pineapple.

That's just silly.

~KMG