After I join the Navy, what happens then?

I am about to join the Navy. I think its one of the best decisions in todays economy. But what im wondering is what happens after basic training. Am i stuck in whatever career role i choose forever or will i have the choice of doing something else. I know i should be talking to my recruiter about this but they like to dodge questions. Id like to be an EOD but if i dont go spec ops right away, will I be able to do so in the future? I just want an up front answer instead of having the recruiter tell me something that may not be totally true.