20-Year Prospect
Considering the amount the U.S. spends on its military, it's safe to say the Coast Guard will still be here in twenty years, rescuing people and keeping our ports safe. With the sea level rising, weather becoming more extreme, and coast lines fundamentally changing, there'll be new and unexpected maritime dangers out there. Don't worry, though, the globe won't become Waterworld any time soon.
If you go to the U.S. Coast Guard Academy and become an officer, you'll be making some serious bucks and have a nice pension to look forward to at retirement (source). You may even be able to snag a teaching position at the academy, especially if you've proven yourself effective as a rescue swimmer. Teaching could push your employment right on through to thirty years easily.