Ask HN: Moving to an unrelated role within a company?

I was recently looking at my company's careers website to find a friend a job posting, and noticed a very interesting opportunity in a new part of the company. I'd like to be considered for the role, but it's entirely unrelated to my current role (I work in engineering/product development, this position is more financially focused). Because of this, I think it's an outside shot that I would get the position. I'm worried to tell my current boss about my interest in the role, as he may assign me to worse projects if I don't get the position. Who should I talk to about the position: the internal recruiter, hiring manager, and/or my current boss? Should I even consider it, or should I just try to find a similar position outside the company?

For some context: I'm currently at my first job outside of college (been here for almost 3 years) and it's a very large company.