Nursing student going 2 the Navy

I am currently a freshman at college and plan on going into the navy after I receive my BSN...unless there are better opportunities for me other than the navy. I want to be in the obstetrics department and was wondering if I would ever have to be in a navy ship if I specialize in this.
What are the physical requirements for me (as a nurse) to get into the Navy? (I am not a very good swimmer...)
How much control do I have on where I work?
I know that some of these questions could be answered at the navy website but I would like some realistic and personal answers.
If you are navy nurse, would you say that this was a good choice?
I know that there are a lot of benefits from being in the navy but not everything is perfect so there must be some cons. Please be honest and share your good and bad stories! Thank you!