Odds of Getting In
Chances are if you try hard and want it badly enough, you'll find some area of the Coast Guard in which to fit. Whether that's as a boatswain mate, a gunner, a pilot, a cook, or an IT techie, all depends on your skill set (source).
If, however, you really want to be a rescue swimmer, your odds of making it into the elite squad are about one in twelve. Class size for rescue swimmers is only twelve and in most cases no more than six or seven of those candidates will graduate. Sometimes as few as two or three will make it, and it's not unheard of for an entire class to fail to graduate.